This PDF file contains the front matter associated with SPIE Proceedings Volume 12757, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The problem of the accuracy of some prints in the field of packaging printing technology due to the inability to accurately detect the thickness of the ink layer is studied. For this purpose, a method of detecting the ink layer thickness by combining the laser triangulation technique and the image processing technique is proposed. Firstly, the platform of the ink layer thickness detection system is built. Then the industrial camera acquires images and processes the acquired images. Finally obtains the laser offset using the improved probabilistic Hough transform method to calculate the thickness value. The experiments verified that the method can effectively measure the ink layer thickness of plastic flexible packaging prints.

Terahertz spectroscopy has many excellent characteristics. This paper uses terahertz spectroscopy to test glucose, fructose, mannose, three kinds of monosaccharides and three binary mixtures according to different mixing ratios. The results show that terahertz spectroscopy is effective in characterizing in the field of similar substances. Based on the experimental data of fructose and mannose binary mixture components, machine learning methods are used to predict the content of each component in the mixture. The prediction accuracy reaches 99.91%, which proves that our model is reasonable. It further proves that the machine learning method combined with the terahertz spectrum of the mixture has an important application in predicting the content of each component of the mixture.

Traditional Hartmann sensors cannot provide accurate incident wavefront information under strong turbulence conditions, and the study of wavefront sensing methods under strong turbulence conditions, which is the key technology of adaptive optical systems. A method using a plenoptic sensor has attracted a lot of attention. Based on the principle of this structure, this paper proposes a method based on the centroid method to reconstruct the wavefront phase. By reconstructing the light field image, the centroid of the number of pixels within the sub-aperture changes. As the slope information is used to restore the wavefront phase, a large amount of phase gradient information can be obtained to reconstruct the phase. In addition, the simulation results show that, based on the plenoptic sensor, keeping the remaining parameters unchanged, the restoration accuracy can be improved by increasing the number of microlenses.

The measurement of multimode quantum fields is a relatively unexplored research area in quantum optics. In this paper, a mode-decomposition scheme termed the frequency-resolved optical mode decomposition (FROMD) is proposed to simultaneously decompose multimode quantum fields into parallel single modes. The mode basis is loaded onto the multifrequency components of the classical local oscillating (LO) field, where one pair of the frequencies that are symmetric with respect to the central frequency of the signal field is modulated by one temporal mode function. Thus, the balanced heterodyne detection using this LO is free of LO excess noise and 3 dB quantum noise penalty. The subsequent multichannel receiver resolves every beat note into the baseband of the signal field. Overall, the output of every channel is in one-to-one correspondence with the measurement outcome of every modal annihilation operator. This is similar to the traditional single-mode homodyne detection.

Based on the first-principles density functional theory, this paper carried out a systematic study on orthorhombic and monoclinic layered-molybdenum trioxide (MoO₃). In particular, its structure, electronic structure, optical properties, and photocatalytic properties are mainly depicted. The results of the studies indicate that Perdew-Burke-Ernzerhof (PBE) overestimates the interlayer distance, while the optB88-vdW reasonably takes into consideration the van der Waals (vdW) interaction and can give a quite satisfactory crystal structure. In addition, the PBE also severely underestimates the band gap, whereas the HSE06 functional can give results in agreement with the experiment. The imaginary part of the calculated dielectric function shows that both structures have an efficient absorption of ultraviolet sunlight. Finally, we also calculated the band-edges of both structures and found the band-edge of MoO₃-II exclusively occupied the redox potential range. Furthermore, the band-edge of layered alpha-MoO₃ contains both reduction and oxidation potentials of the water, suggesting that alpha-MoO₃ is a potential photocatalytic of water-splitting.

The study compared the enhancement effects of vertically polarized double pulse (DP) and quadruple pulse (QP) femtosecond lasers on the laser-induced breakdown spectrum (LIBS) of fused silica, and by analyzing the ratio of multi-pulse ablation volume to single pulse and the change of surface morphology, combined with electron dynamics to explain the mechanism. The results show that at 0.47ps and 7.68ps delay, the ablation volume change caused by photon absorption plays a leading role in the enhancement of LIBS signal, and the signal intensity of DP and QP LIBS is almost the same; at 15.42ps delay, the volume ratio of multi-pulse ablation is basically unchanged, plasma reheating and slow plume component reionization play a leading role, QP signal enhancement effect is stronger than DP, but the ablation volume is only 1/2 of DP. The results show that for dielectric materials such as fused silica, the LIBS of QP femtosecond laser can achieve higher spatial detection resolution than DP, under the premise of ensuring that the excited plasma intensity is not weak or even stronger

The experimental results of laser welding of dissimilar alloys between Mg-Li and Ti alloy with different LSOs show that the IMC around the interface of LZ91 and TC4 improves the bonding strength of the BMs. When the LSO is -0.2mm, Mg₁₇Al₁₂ in the weld is evenly distributed in the α-Mg and β-Li solid solutions. At this time, the average microhardness and the tensile strength of the weld joint provided acceptable performance, 73.05HV and 124.06MPa, respectively.

In this experiment, the LZ91 Mg-Li alloy and TC4 titanium alloy were joined with a thickness of 2 mm by using a fiber laser, which investigated the effect of beam stirring frequency on the microstructure and mechanical properties of welded joints. The results showed that the oscillation of the beam would improve the molten pool stirring driving force and helped the Al element in the base material of TC4 titanium alloy flow to the molten pool, which caused the Mg-Al reinforced phase precipitated at the intersection of LZ91 and TC4 to significantly improve the bond strength of the weld, with the maximum microhardness reached 71.32 HV and the maximum tensile strength reached 153 MPa.

An optical coupling interface is a crucial component in Silicon Photonics (SiPh) technology for optical signal transmission. It is widely utilized to achieve on-chip light sources and optical input/output for SiPh chips. In this work, we report a coupling interface with a focusing structure based on the 3μm SOI waveguide platform to minimize mode profile mismatch, resulting in a high coupling efficiency and relatively large -1dB alignment tolerances across a wide bandwidth. Simulation results show that our design achieved a high transmission of greater than -0.85dB across the 1500-1600nm range, with a maximum of -0.847dB. When the laser is positioned 1.5μm away from the waveguide facet, the -1dB tolerances are ±0.62μm and ±0.45μm in the horizontal and vertical directions, respectively. Additionally, the interface is safe for lasers as it has a return loss (caused by reflection) of less than -30dB.

By analyzing the principle of polarization detection, a method of identifying unexploded ordnance using polarization spectral information is presented. Then a polarization hyperspectral detection system was designed. Finally, the system was used to conduct detection experiments on mines in the background of cluttered grass at 400-1000nm band. The experimental results indicated that the polarization characteristics of the unexploded ordnance and the natural background were different, and the use of polarization detection technology could well distinguish the unexploded ordnance from the natural background and improve the accuracy of target detection and scene identification, especially in the 450-800 nm band to achieve effective detection and identification of camouflaged targets from the cluttered background.

Extreme ultraviolet lithography (EUV) is a key technology for micro-nano processing and is widely used in the chip manufacturing process. Mask optimization is one of the key resolution enhancement techniques in EUV lithography. In this paper, a thick mask optimization method based on particle swarm optimization (PSO) algorithm is proposed to improve simulation accuracy and imaging quality. In this work, we change the calculation order of formulas, which is used to accelerate the imaging calculations. The equivalent film layer method is used to approximate the reflection coefficients of thick mask multilayer film structures to improve the simulation accuracy. The inverse lithography problem for thick mask optimization is solved by particle swarm optimization algorithm. The simulation results show that this method can effectively improve the simulation accuracy and imaging quality.

In the field of unpatterned wafer inspection, the biggest market share is dark field defect inspection, in which the signalto-noise ratio limits the detection limit. In order to improve the signal-to-noise ratio of the optical detection method based on the theory of dark-field scattered light. In this paper, the influence of the polarization characteristic of light on the scattering field is studied, and the signal-to-noise ratio of the scattering signal can be improved by controlling the polarization component of light. The results show that modulating the polarized light can achieve a higher signal-to-noise ratio.

Due to the limitation of standard quantum limit (SQL), traditional laser interferometry based micro angle attitude measurement technology cannot further improve its measurement accuracy. Applying quantum weak value measurement technology to micro angle measurement will greatly improve its measurement accuracy. This article introduces the basic principle of quantum weak value measurement, and introduces the research progress in micro bit angle/displacement measurement using quantum weak value measurement technology in recent years. The future application trend of quantum weak measurement technology in micro angle is analyzed and prospected.

A new focusing crystal spectrometer based on a planar crystal array was developed for simultaneous diagnostics of the X-ray diffraction spectrum and integrated time spectrum. In the crystal array, flat crystals were distributed in a circular shape. A coaxial annular optical fiber array was arranged perpendicular to the dispersion direction and each ring collected X-ray diffraction with different energy. The ray tracing method was used to analyze the spatial distribution of diffraction. A prototype was built and the process of X-ray pulse and the relative intensities of the characteristic X-rays Cu-Kα and CuKβ were measured. The result showed that the X-ray pulse lasted about 80ns, with a rising time of 30ns. There was a plateau period of 10ns during the falling time. The intensity ratio of Cu-Kα and Cu-Kβ experienced a process of rapid descent stabilization and slow ascent, the ratio was stabilized at around 1.5 nearby the Emission intensity peak.

With the continuous advancement of communication technology and the increasing popularity of new energy vehicles, the performance expectations of traditional first and second generation semiconductors are no longer being met. Therefore, current research has shifted towards third generation semiconductors, such as GaN, due to their unique material properties. GaN offers a higher electron saturation drift rate, more robust radiation resistance, and higher thermal conductivity. GaN HEMT, which is based on GaN, has attracted much attention in high power and high-frequency scenarios, owing to its higher breakdown voltage and electron mobility than traditional silicon-based semiconductor devices. This paper explores the current applications of GaN HEMT in DC-DC power converters for electric vehicles, as well as power amplifiers and low noise amplifiers for wireless communications. Additionally, the present application of GaN HEMT is critically assessed, and potential future development or improvement directions are discussed. Given its exceptional material properties and unique advantages, it is anticipated that GaN HEMT will continue to play a crucial part in the development of advanced semiconductor devices

In this paper, the methodology of real-time pesticide proportioning by spectral analysis technology is proposed for the first time. Used 0.5% Matrine as the research object. The spectral analyzer, flow cuvette, and peristaltic pump, etc., were combined used to create a real-time proportioning model. Specifically, the spectral data, which corresponding to different concentrations of Matrine under the transmission of the same light source, were measured. And then, its effective information was extracted for analysis. Finally, the least squares method was used to create the proportioning model. Through the experimental study, it can be demonstrated that the significant correlation between Matrine concentration and light intensity, with a linear R² of 0.93632, which correspond to the spectrum peak and Matrine concentration range from 659 nm, and 1.2 to 3.2ml/kg, respectively. In this paper, the viability of applying spectrum analysis technology to achieve pesticide formulation was proved. The system structure is simple, and effectively avoid the eliminating sophisticated control algorithms and system modeling, which can serve as a theoretical framework for accurate pesticide formulation.

An optical true-time delay generation scheme based on WSS for adaptive null steering is proposed. The system is based on optically-switched fiber TTD technology. Take the advantages of the LCoS-based programmable WSS, arbitrary multiple true-time delays to generate multiple nulls can simultaneously be synthesized by control the routing of the optical radio frequency signal between the wavelength selective switches. We simulate the scheme with Optisystem and Matlab, the results confirm the scheme is able to achieve null depth over 50dB.

In recent years, the automated observation calibration of satellite remote sensing sensors has been widely used. At least 2~3 automated observation devices are usually required to complete the collection of necessary parameters such as surface reflectance, aerosol optical depth, and sky scattering radiation in the calibration field. In this paper, a high-precision automated ground-solar-sky radiometer (GSSR) is developed, which provides 9 working modes, including direct solar irradiance mode (SUN), solar almucantar scanning mode (ALM), almucantar in the hemisphere scanning mode (ALMH), solar principal plane scanning mode (PPL), principal plane in the hemisphere scanning mode (PPLH), ground observation mode (GRD), in-orbit synchronization mode (SYNC), sky radiance channels calibration mode (SKYCLB), and ground radiance channels calibration mode (GRDCLB). The 9 working modes can realize the automatic measurement of direct solar irradiance, sky diffuse irradiance, and ground radiation with high accuracy, and then invert the basic parameters required for vicarious calibration in site of satellite remote sensing sensor. It can realize the absolute radiation calibration of visible-near-infrared wavebands when the satellite remote sensing sensor overpass by one instrument only by itself. At the same time, the long sequence of sky diffuse and ground radiance measurement data is helpful for analyzing the evolution of atmospheric and surface spectral characteristics in the calibration field over a long period.

A new composite-designing method of computer-generated holograms (CGH) is proposed to generate Bessel-like beams with complex transverse intensity distributions that propagating along arbitrary trajectories. In this method, the radial and azimuthal distribution of phase are regarded as two independent variables and designed separately, so that the Bessel-like beam can be three-dimensionally (3D) manipulated. Furthermore, on the basis of that method, more complex nondiffractive beams can be generated by coaxial/non-coaxial interference of multiple beams. Laser beam spatially shaping can be realized by loading the pre-designed phases onto a spatial light modulator (SLM). These may have potential applications in optical trapping, microholes fabrication and two-photon polymerization (TPP) technology.

Here, we demonstrate a field-deployable free-space optical link for quantum key distribution (QKD) between a ground station and radio-controlled electric vehicle (RCEV). Compact and high-performance acquisition, pointing and tracking (APT) system is developed for small tracking error down to 3.8 μrad and average link loss of 16 dB. Such link is within the requirement of normal QKD system. With automatic acquisition and coarse tracking, the APT system can automatically establish the free-space optical link in 10 minutes. It is the first step towards mobile quantum secure communication network. Based on RCEV, the quantum optical link can be reconfigured at different link distances. This result greatly improves the flexibility of the link construction for the future QKD applications.

High-finesse optical enhancement cavities (OECs) are powerful and versatile tools for various scientific investigations and measurements. They offer superior optical performance and have been widely researched and utilized. Finesse is a crucial parameter for OECs. It is essential to measure finesse accurately for OEC applications. Here, we outline the current development and potential applications of high-finesse OECs and introduce several finesse measurement methods. An OEC system with a length of 3.78 m is built and stable locking is achieved. Finally, the finesse is measured experimentally to be approximately 15,000 by the free spectral region (FSR) modulation method.

Aiming at the problem that the traditional range optical measurement data processing software does not fully consider the characteristics of the observation equipment, which leads to the time-consuming and laborious data processing, a range optical measurement data processing and analysis system for range optical measurement data processing is designed and developed. The system includes image interpretation substation and data processing substation, and integrates multiple functional modules such as test image interpretation, data preprocessing, error correction, coordinate management, trajectory visualization display, multi station rendezvous, attitude measurement, velocity measurement, etc. The system adopts the architecture mode of front end and back end separation, realizes the front end and back end message communication through Web API, and realizes asynchronous data calculation and rendering display. User rights and role management are added to ensure the security and reliability of data storage.

We proposed a 2×2 SOI thermo-optic switch based on microring assisted Mach-Zehnder interferometer(RAMZI) and graphene heater. The thermo-optic switch consists of 2×2 MMI-based 3-dB coupler, and RAMZI with graphene film as heater fixed above the microring resonator. A design and optimization of the switch, including optical characteristics of MMI coupler and MZI, electro-thermal characteristics of graphene heater and the overall performance of the switch, is carried out. The thermo-optic switch is demonstrated with small footprint of 0.07 mm2 , and low power consumption on simulation.

In order to further improve the frequency discrimination ability of fiber optic vibration sensor, this paper uses the multimode fiber (MMF) coupler to construct the Sagnac interferometer, which combines the multimode interference with Sagnac interferometer. Multimode fiber couplers with splitting ratio of 1:1 were fabricated by using MMFs with core diameters of 105 and 62.5 μm respectively, and the Sagnac loops were constructed with the couplers. For comparison and analysis, single-mode-multimode-single-mode interference structures and Mach-Zehnder interferometer were also fabricated by MMFs respectively. Furthermore, single mode fiber based Sagnac loop was also fabricated. Through a large number of experiments, these structures were used to measure vibration frequency, and their performance were compared in detail in the frequency range and the frequency accuracy of vibration detection. The results showed that the intensity difference between the primary peak and the secondary peak of the frequency spectrum obtained by the Sagnac interferometer with the core diameter of 105 μm step-index MMF is greater than 20 dB in the range of 0.3 to 20 kHz with frequency deviation in the order of Hz. With the large detectable frequency range and frequency recognition capability and higher sensitivity to the low frequency vibration, the Sagnac interferometer combined with multi-mode interference provided by the 105 μm step-index MMF is a kind of structure with the best performance among these studied structures in vibration measurement, which provides a new scheme for the research of vibration detection.

Continuous carbon fiber reinforced thermoplastic composites have problems such as long temperature self setting time, high overshoot, and low control accuracy during laser in situ molding, resulting in poor component forming quality. This article designs a temperature closed-loop control system based on an intelligent fuzzy proportional-integral-differential (PID) controller. By introducing a fuzzy self-tuning PID algorithm, the goal of quickly adjusting to the working temperature when turned on is achieved. The temperature overshoot is significantly reduced, and the temperature control accuracy is improved. According to the requirements of laser in situ forming of carbon fiber reinforced polyether ether ketone composite materials, a laser in situ forming experimental device was built. Through simulation testing and comparison of forming temperature, the results showed that compared with traditional PID controllers, when using an intelligent fuzzy PID controller to control temperature, the temperature control accuracy was maintained at ± 10 ℃, the overshoot percentage was about 2.29%, and the adjustment time was about 9.7 seconds. All indicators met the actual engineering requirements, The temperature setting effect is good and the fitting degree is high. Therefore, the overall performance of the intelligent fuzzy PID controller is far superior to traditional PID controllers, meeting the temperature control requirements in the laser in situ molding process of thermoplastic composite materials.

Compressive sensing theory can reduce the cost of image processing, which can be used in many fields. Based on the sparse characteristics of space target image, this theory has a good application prospect in the field of space optical observation. The practical application of compressive sensing contains three steps: sparse representation, coding measurement and sparse reconstruction. This paper applies compressive sensing theory in optical imaging of space target by learning dictionary sparse representation, non-coherent measurement matrix and orthogonal matching pursuit reconstruction. In order to study the effect of this application, the evaluation index is constructed by peak signal-to-noise ratio and structural similarity. The simulation results show that this theory can sense the space target in low data amount and reconstruct the image in a good quality. This conclusion provides a feasible method for the application of compressive sensing in space-borne imaging system.

UV-LED is popular in the disinfection industry due to its advantages of being environmentally friendly, easy to set up, and small in size. The pulsed irradiation of UV-LED, which has significant reference value for effective sterilizing and longlasting bacterial suppression, is used in this research to study and execute a pulsed UV disinfection approach. The study concentrated on the effectiveness of pulsed UV light in inactivating E.coli and inhibiting its photoreactivation. According to the experimental findings, when the peak optical power of pulsed UV was enhanced by 8.4 times, the log inactivation value increased by 2.6 times compared to continuous UV, and the photoreactivation rate decreased by 21.1% in just 4 hours. Achieved were the consequences of effective sterilization and photoreactivation inhibition.

The 3D quasi-spherical focal spot and optical ring may find potential application value in fields like arbitrarily oriented particle capture and guidance, super resolution microscopy and optical capture. On the basis of the radiation pattern of the orthogonally superimposed dipoles antenna in a 4Pi focusing system, this paper firstly proposes an approach to create a central pure circular polarization three-dimensional (3D) quasi-spherical focal spot with higher longitudinal resolution. In addition, we also use the radiation pattern of the ring array antenna composed of orthogonally superimposed dipoles antenna elements to flexibly generate a pre-parameterizable and uniformly distributed optical ring. The simulated numerical results show that the method achieves a quasi-spherical focal spot with a slightly smaller longitudinal size (~0.31λ) than the transverse size (~0.41λ), and with the smallest volume (~0.0273λ³ ). The position, radius, ring number and layer number of the constructed optical ring can be adjusted arbitrarily, determined by the parameters of the ring array antenna.

We proposed an ultra-wide-band microwave photonics flexible frequency conversion scheme for integrated electronic systems, meeting the requirements of frequency conversion for multifunctional signal without crosstalk. The reconfigurable microwave photonics filter is exploited to achieve the flexible segmentation of optical broadband microwave signal with different center frequency and elastic bandwidth. The LO optical signal adapted to the signal frequency and target IF frequency is provided by the signal optical carrier, and the carrier-suppression single sideband mode of DPMZM ensures the flexible frequency conversion function. The numerical simulation of the proposed scheme is introduced to verify the feasibility and effectiveness, and three analog wideband signals are flexibly and efficiently converted to the target frequency with almost no crosstalk interference.

The high-frequency and tunable microwave signals are highly desirable in the files of military and civilian. The microwave photonic technology is an important solution to generate high-frequency and tunable microwave signals. Among them, the integrated microwave photonic solutions have a broader application prospect due to its small size, large bandwidth, and low power consumption, etc. We demonstrate a design of the monolithic integrated coupled DFB lasers (IC-DFB) to generate tunable microwave signal. A semiconductor optical amplifier (SOA) is integrated between DFB lasers to adjust the coupling strength. By tuning the injection current of the SOA section, microwave signals with a tuning range from 31 GHz to 35 GHz is achieve.

The traditional interferometry only uses laser light source, because of the ultra-high coherence rate of laser, there will be great crosstalk in the detection of special optical devices such as parallel plate and prism. LED, tungsten lamp and other traditional light sources are not suitable as ideal light sources for testing interferometers of special optical components because of their poor collimation, poor laser intensity stability and short coherence length. The short coherence superposition laser illumination source has the advantages of good directivity, high brightness and moderate coherence length, so it is an ideal light source for special components to detect interferometers. As a new type of semiconductor device, laser is widely used in people’s life, but its problems are also obvious. In this paper, modulation of short coherent light source based on photoelectric effect is studied. The paper initially introduces the realization and optimization of the short coherent light source, then analyzes the longitudinal modeling of the semiconductor laser, and calibrates the semiconductor laser. Finally, based on the photoelectric effect, a short coherent light source is proposed to replace conventional electroluminescent devices with certain reliability, low cost and stability.

The thermal lens calculated by numerical calculations plays a significant role in the non-planar ring oscillator (NPRO). And the temperature, strain, and face bugling required for the calculation are obtained by finite element analysis methods. According to the finite element analysis, we can easily know that the maximum temperature of the crystal is 306.5K and the maximum thermal strain is 1.0E-4 with 3W pump power. What most important in the optical path difference analysis is the thermal lens induced by temperature. In this work, we provided the data for studying the influence of thermal lens on loss difference and made the thermal model refined, which is the basis for an optimized resonator design with high power and narrow linewidth seed light source systems.

In this paper, the optical power of a vertical cavity surface emitting laser (VCSELs) orthogonal line polarization light was measured and analyzed at different liquid crystal (LC) layer design using a nematic LC layer as a laser polarization control unit integrated into the surface of VCSELs. The experimental results show that, after the integration of the LC, as the design of the LC layer increases, the first jump point of laser polarisation is gradually delayed, and the current value ∆I between the first and second jump points gradually increases, with the design of the liquid crystal layer being 10µm, ∆I is 2.5mA, which is 1.5 times higher than without the LC. It can be seen that by varying the design of the surface LC layer, the orthogonal line polarization stabilization range of the VCSELs can be effectively extended, which provides a theoretical and experimental basis for the design and fabrication of high quality single polarization stabilized LC-VCSEL.

Based on the principle of synergic radiation of double flame agent, a yellow light signal agent formula of red and green double flame agent is proposed, and the wavelength can be adjusted in the range of 576.4~591.3nm, the color changes from light yellow to dark yellow. Based on the theory of double flame agent synergetic radiation, the main illuminant components are Ba(NO₃)₂, SrNO₃, Mg, shellac and PVC, to realize the yellow light color adjustable, and the best formula of yellow light color close to the traditional sodium salt illuminant was determined, and the flame combustion spectrum and luminous intensity of the illuminant were tested. The experimental results show that: By adjusting the ratio of two colors of flame, yellow illuminant with different wavelength and color purity can be obtained. When the ratio of Ba(NO₃)₂ to SrNO₃ is 3:1, the color is more suitable for human observation, the formula is 40.5 % Ba(NO₃)₂, 13.5 % SrNO₃, 40 % Mg, 2 % shellac and 4 % PVC, the luminous intensity is 222540.72cd, the wavelength is 587.5nm, and color purity is 74.1%.

Photocatalytic reduction of CO₂ technology is an important solution to environment difficulties. Due to the shortcomings of photocatalyst itself, such as weak response to light, it is necessary to improve the photocatalyst to adapt to industrialization. In this paper, the photocatalyst Bi₂WO₆ /g-C₃N₄ was designed and prepared by one-step hydrothermal method, and its photocatalytic performance was tested through the photocatalytic reduction experiment of CO₂. Through the verification of various physical and chemical characterization methods, the excellent CO₂ reduction ability of Bi₂WO₆ /g-C₃N₄ composite photocatalyst was discussed. Due to the establishment of its Z-type heterostructure, this structure enhances the transmission speed of photogenerated carrier, reduces the recombination rate of electron hole pairs, improves the utilization rate of photons.

Laser square wave pulse plays an important role in the application of high power optical field. In this work, the modulation phase signal corresponding to the square wave pulse is inversely solved by the method of numerical calculation. And a modified modulation method is proposed, which can generate the coherent square pulse train with constant frequency interval in the frequency domain. It has the potential to provide a solution for the application requirements of high power optical field. In addition, the error analysis of the delay time in the double modulation model is carried out, and the influence of different time delay on the generated square wave pulse deformation is considered qualitatively and quantitatively in one cycle, which provides a theoretical basis and feasibility analysis for the experiment implementation

In this paper, the nematic liquid crystal layer is used as the laser polarization control unit, which is integrated on the surface of the vertical-cavity surface-emitting laser (VCSEL) array. The optical power anisotropic loss characteristics of the orthogonal polarized light emitted by the VCSEL array when passing through the nematic liquid crystal with different rotation directions and the resulting impact on the polarization characteristics are measured and analyzed. The experimental results show that the maximum orthogonal polarization suppression ratio (OPSR) of VCSEL array increases from 2.31dB to 5.05dB when the rotation direction of the liquid crystal is adjusted from 45° to 0°, while the 90° rotation can completely eliminate the polarization switching, and obtain a stable output of single polarized light. The experimental results provide a new scheme for VCSEL single unit and array to achieve high quality single polarization output

The liquid zoom lens through remote control was reported which consisted of zoom module and remote control module connecting by a plastic tube. The Dowconing SYLGARD 184 silicone was employed to fabricate the elastic film to cover the upper surface of the liquid chamber of the zoom module. The remote control module was similar to the needle tube that can extrude or extract the liquid from the zoom module by the plastic tube. The variable liquid chamber resulted in the elastic film transformable so variable focal lengths can be obtained. The design of the liquid lens was represented in detail. The finite element analyses (FEA) was carried out and its image quality was demonstrated. The liquid zoom lens through remote control is potentially applied in remote control systems such as endoscope, dangerous or minitype environments.

In this work, a chemical sensor for concentration measurement of hydrogen peroxide is proposed based on localized surface plasmon resonance (LSPR). The silver nanoparticles coated by polyvinyl alcohol (PVA) have been prepared by the reduction process of silver nitrate (AgNO₃) in aqueous PVA matrix. The LSPR wavelength of the Ag-PVA nanocomposites is 420nm, as measured by ultraviolet -visible spectrometer. When hydrogen peroxide is added into the solution of Ag-PVA nanocomposites, the silver nanoparticles become degradation during the decomposition of hydrogen peroxide. In this process, the light absorption caused by LSPR effect is reduced obviously. Based on this mechanism, the concentration of hydrogen peroxide can be determined by measuring the change of transmission power through the AgPVA nanocomposites. In our experiments, the threshold detection level of the sensor is less than 10-3M. Besides the chemical sensing applications, the proposed system can be also used to analyze the generation process of silver nanostructures under UV light illumination.

In order to analyze the mechanism of optical chirality signal enhancement of chiral spherical particles, the scattering properties of chiral particles were studied based on the T-matrix method, and the optical chirality signal is calculated under different types of polarization vortex beams with orbital angular momentum (OAM). Firstly, for particles with fixed sizes, the enhancement effects of tightly focused light field of radial and azimuthally polarized polarization beams were explored. In addition, for particles with varying sizes, the enhancement of the optical chirality signal of particles was achieved by controlling the order of OAM carried by the beam.

Vertical cavity surface emitting laser (VCSEL) array is the important laser source in LiDAR ranging systems (LiDAR). The VCSEL array have important effects on the electro-optical transient response characteristics and power density for time-of-flight ToF ranging technology. In this study, by using the carrier-photon coupling equation of semiconductor lasers, we established a Simulink model of the rate equation of pulsed VCSEL arrays, an equivalent circuit model and a heat dissipation model of VCSELs. We analyzed the factors affecting the electro-optical transient response of pulsed VCSEL arrays theoretically. Then we verified the result experimentally. In this paper, the effects of array size and spurious parameters on the electro-optical delay time and optical pulse rise time of VCSEL arrays are discussed. Both simulation and experimental results show that the rise time of the VCSEL array decreases and then increases as the size of the array increases in the narrow pulse driving circuit. This provides a light source optimization scheme for the application of VCSEL arrays in LiDAR ranging systems (LiDAR). It also provides a theoretical basis for the in-depth study of VCSEL arrays under pulse driving.

In recent years, the study of topological phases has been highlighted in condensed matter physics. Generally, the anisotropic electromagnetic media are topologically trivial because of broken the three-dimensional rotational symmetry. In this paper, by injecting the external current, we restore the rotational symmetry of the anisotropic electromagnetic media, so that the topological phases of these systems can emerge. This study will provide an alternative way to explore the topological phases of the anisotropic electromagnetic media.

Metal corrosion plays a crucial role in many fields and a large number of methods have been developed to improve corrosion resistance. Inspired by pitcher plants, slippery liquid-infused porous surface (SLIPS) has attracted much interest in corrosion prevention because of their excellent water resistance. In this study, we proposed a novel method for fabricating porous micro/nanostructures on aluminum using a temporally shaped femtosecond laser combined with fluorination, followed by the immersion of an all-ether polyfluorinated oil in the fluorinated porous micro/nanostructures to obtain SLIPS. This SLIPS demonstrated excellent resistance to water and liquids with low surface tension, stable storage behavior, excellent anticorrosion properties, and mechanical stability. It also remained smooth for more than 3 months. Abrasion tests demonstrated that despite the heavy physical damage sustained by the SLIPS, its surface rapidly self-healed without additional treatments and regained its slipperiness. Electrochemical impedance spectroscopy revealed that the super-hydrophobic surface (SHS) and SLIPS enhanced the corrosion inhibition performance, with the SLIPS exhibiting superior performance. The corrosion resistance of the SLIPS was one and three orders of magnitude greater than that of the SHS and bare Al, respectively. In summary, we proposed a convenient and effective method for preventing metal corrosion in industrial settings.

In this paper, the effect of nanosecond pulsed laser pulse width on the effect of laser cleaning of 2A12 aluminum alloy surface composite coating is discussed. By establishing a simulation model of nanosecond pulsed laser paint removal, and conducting experimental research on nanosecond pulsed laser cleaning of 2A12 aluminum alloy, the temperature field of 2A12 aluminum alloy surface composite coating under different laser pulse width conditions was recorded and analyzed by thermal imager and spot pyrometer, and the surface morphology of the substrate was observed by metallographic microscope to explore the influence of laser pulse width on the surface composite coating of 2A12 aluminum alloy by nanosecond pulse laser cleaning. The experimental results show that the cleaning effect is better when the pulse width is 200ns under the condition of average power of 45W and frequency of 130kHz scanning speed of 2.5mm/s, at which time the coating is basically removed and the oxide film of the aluminum alloy substrate is revealed. In the process of nanosecond pulsed laser cleaning aluminum alloy, the pulse width of the pulsed laser has a greater influence on the temperature, and the wider the pulse width of the pulsed laser, the longer the temperature rise time and temperature rise duration of the surface material, and the thermal effect of the laser cleaning effect is also more obvious. When the pulse width is narrower, the peak temperature is higher and the continuous temperature rise time is shorter.

Compared with traditional cleaning, laser cleaning has many advantages such as green, environmental protection and easy control, and it has a wide range of application prospects. In this work, the cleaning of single paint layer and composite paint layer on the surface of 2024 aluminum alloy was experimentally studied under different powers. By observing the surface morphology of aluminum alloy after paint removal, the cleaning thresholds of different paint layers are obtained, and the ideal cleaning thresholds of different paint layers under laser cleaning are compared. The results show that when the laser frequency is 120kHz, the pulse width is 200ns, the scanning speed is 4.5mm/s, and the laser power is 45W, the ideal cleaning threshold for the single paint layer is achieved. When the laser frequency is 120kHz, the pulse width is 200ns, the scanning speed is 4.5mm/s, and the laser power is 38W, the ideal cleaning threshold of the composite paint layer is achieved, and compared with the cleaning threshold of different paint layers, the cleaning threshold of the composite paint layer with thicker paint thickness is significantly lower than that of the single paint layer with thinner paint layer, and the reasons for this phenomenon are analyzed.

With the development of femtosecond laser processing technology, and the demand of practical application, it is more and more required that the research and application of femtosecond laser processing technology turn from single system to composite system. In this paper, by studying the ablation crater shape, Raman spectral characteristic peak and micro/nano structure evolution of femtosecond laser processing of double-layer films (DLC/TiN, the Vickers hardness is all greater than 2000 GPa, greater than 40 GPa is called ultrahard material) with pulse number, the femtosecond laser ablation removal rule of double-layer films (DLC/TiN) was discovered, that is, the graphitization modification of the first layer of diamondlike carbon film (DLC/ TIN) would first occur with laser pulse deposition. Then a "mountain dome" shaped bulge is generated, and the bulge is removed at the center, and the ablation crater is generated with nearly linear depth and pulse number, that is, the ablation removal rate of the upper and lower layers is consistent. It can provide important reference for femtosecond laser processing of microholes, microgroove and complex patterns on double-layer films (DLC/TiN), and expands the application of laser

Lithium titanate batteries are widely used as an energy source for high energy laser systems. In order to improve the reliability of high energy laser systems, this study established a life prediction model for lithium titanate batteries based on the classical one-dimensional Wiener process, adopted the Bayesian method for remaining useful life (RUL) prediction, and updated model parameters with typical working condition data from similar products to improve prediction accuracy, narrowing the prediction confidence interval to within 10 cycles. Experimental results show that the proposed method has high accuracy and feasibility.

Carbon fiber reinforced polymer (CFRP) is widely used in aerospace, transportation and other fields due to its excellent material properties. In order to improve the adhesive bond strength of CFRP composites, surface treatment is particularly important. In this study, femtosecond laser was used to treat the surface of aerospace high modulus CFRP composites, and the changes of resin removal and micro/nano structure of carbon fiber with laser fluence were investigated. It was found that the improvement of wettability was more favorable under the condition of removing the ablated resin and forming the complete micro/nano structure on the surface of carbon fiber. Through optimization, changing the laser fluence used in surface treatment, the water contact angle of the treated surface was reduced from 111.9° to 7.5°, greatly increasing the hydrophilicity of the surface, significantly enhancing the ductility of the surface liquid, which is expected to promote the flow and penetration of the adhesive on the surface, and further enhance the bond strength.

MXenes exhibit exceptional optical and plasmonic properties and have been widely used in sensors and optoelectronics. Understanding the charge carrier dynamics is crucial in guiding the design of these applications. In this study, we used transient absorption spectroscopy to investigate the ultrafast carrier dynamics of the metallic Ti₂CT_x and the semiconductor-like Nb₄C₃T_x. Although both Ti₂CT_x and Nb₄C₃T_x demonstrate surface plasmon (SP) absorption properties, their SP recovery dynamics differ due to the variation in free carrier density and electron-phonon scattering strength. Metallic Ti₂CT_x has a greater free carrier density nearby the Fermi level, which leads to strong electron-phonon scattering and low thermal conductivity. In contrast, semiconductor-like Nb₄C₃T_x displays a fast decay of photoinduced bleach (PB) dynamics due to the trapping of hot electrons, followed by hot electron relaxation and recombination. Our findings shed light on the SP properties of both metallic and semiconductor-like MXenes, which have important implications for the preparation of MXenes devices and their application in the field of photothermal and optoelectronic applications.

The rotational Doppler effect provides a non-contact way to detect the angular velocity of a rotating rough surface. Previous research focus on the condition that the axis of structured beam is aligned with rotational axis. However, it is hard to align the axis of beam and rotational axis especially in remotely detection and behavior of rotational Doppler shift in misaligned arrangement is still unclear. Here, we investigate rotational Doppler effect in misaligned arrangement from the view of Doppler shift distribution. Based on the Monte Carlo method, the influence of scatterer which is a random rough surface is considered in the analysis of misaligned RDE. The variation of spectrum of fundamental scatter mode in misaligned illumination is revealed, which may provide theoretical reference for the measurement of angular velocity based on RDE.

The minority carrier lifetime is an important parameter to determine the operating characteristics of HgCdTe infrared detectors, and surface recombination reduces the minority carrier lifetime of HgCdTe alloys. To analyze the effect of surface recombination on the measurement of minority carrier lifetime, the minority carrier lifetime of HgCdTe alloys samples with different thicknesses was tested by microwave photoconductivity decay method, and the practical minority carrier lifetime, surface recombination rate and minority diffusion coefficient of HgCdTe alloys were calculated based on the measurement results. In addition, to reduce the effect of surface recombination on the minority carrier lifetime, the surface of HgCdTe was passivated. The test results show that the minority carrier lifetime decreases rapidly as the HgCdTe film thickness decreases. When the thickness of the sample is below 13 μm, the influence of the recombination on the minority carrier lifetime measurement results should be considered. And the minority carrier lifetime of HgCdTe increases after passivation.

The increasing demands for enhance information security in the national defense and military applications such as satellite communication and integrated RF front end, have led to a critical requirement for high-speed frequency-hopping systems. However, the traditional frequency-hopping systems which is based on electrical domain is limited by its own electronic bottleneck. For example, the bandwidth is generally limited to several GHz, and the speed is generally limited to ms. Therefore, this paper innovatively propose a frequency-hopping system which has wide hopping-frequency bandwidth and frequency-hopping speed by using microwave photonics. The system has a frequency hopping bandwidth of more than 70GHz, a hopping speed of up to ns, and a maximum support of 35 frequency points, which can greatly expand the application prospect of secure communication.

In a solar thermal power generation system, image processing of the reflected light spot of a heliostat is a very important part of the system, which greatly affects the thermal conversion efficiency of the heliostat, and the calculation of the center point of the reflected light spot is a crucial part. To ensure the accuracy and efficiency of center positioning in the calculation of heliostat reflected light spot center points, this study suggests a technique that combines the Steger method and the grayscale center of gravity method. Through building a test site, collecting light spot data, and conducting experimental verification, the results show that under strong light conditions, the approach suggested in this article is more accurate in determining the center point than the established gray center of gravity method. and the calculation speed is also faster, providing a reference for subsequent research on the calculation of the center point of the heliostat reflection light spot.

In recent years, bound states in the the continuum (BIC) on optical metasurfaces have received a lot of attention due to their unique properties. In this paper, an all-dielectric metasurface based on dual symmetry-protected BIC is proposed. By adjusting the in-plane symmetry of the structure by the size of the circular etch hole, dual quasi-BIC with high Qfactor can be generated, and the modes are analyzed by multipole expansion and near-field electromagnetic distribution. To further change the degree of asymmetry, dual quasi-BIC modes can be shifted and Q-factor adjusted. Finally, due to its potential for high sensitivity and flexible manipulation, this all-dielectric metasurface is well suited for Label free refractive index biosensing, enabling compact sensing devices for a wide range of applications.

The precision of frequency signal is constantly improving, and the application of high-precision frequency signals requires an equally high-precision transmission method. So in this paper, we demonstrate an optical carrier radiofrequency phase stabilization transfer system based on a phase lock loop (PLL), applied to a 20 km spooled fiber link. The phase noise induced by optical fiber is suppressed by the PLL, and the transfer stability improved from 7.2×10^-13@1 s to 8.9×10^-15@1 s. In addition, the phase difference of peak-to-peak with compensation is less than 10 ps in a measurement of about 1 day. The phase study in antenna is with the compensation mode, so this work will lay the foundation for the phase synchronization of distributed coherent antenna system.

Energy storage systems can effectively improve the inertia of PV systems and achieve power smoothing of PV power generation due to their fast and flexible power regulation capability. This study proposes a BESS charging and discharging control method with limited PV fluctuation smoothing for the capacity optimization of energy storage in high permeability PV grids. This method can reduce the number of times the BESS is charged and discharged and improve its service life while smoothing out large fluctuations in PV power output.

Two 808 nm semiconductor lasers were combined by V-shaped spectral beam combining and locked at 798.8 nm, and 800.5 nm respectively. The outpower power and beam quality in the slow axis were improved significantly. The sum frequency of semiconductor lasers was realized based on the laser source. A laser with an output power of 6.5 W and beam quality of M² = 2.2×18.5 was obtained by the spectral beam combining. The M² in slow axis was improved by 30% and the combining efficiency was 83%. The 399.9nm sum frequency laser at a power of 18.3mW was obtained and the efficiency of sum frequency generation was 0.28%.

Non cooled infrared thermal imaging cameras require external DC power supply. In practical applications, there may be abnormal situations where the power supply is reversed, and the actual power supply voltage exceeds or falls below the required voltage of the camera^[1]. Traditional camera power modules do not have protective circuits or power noise suppression functions, which can cause camera damage and a decrease in infrared imaging quality. In response to this issue, this article proposes a circuit design based on the ADI power management chip LTC4365ITS8 # TRMPBF, which integrates EMI suppression, under-voltage, over-voltage, and power reverse protection functions, and has a light alarm function. Example verification and analysis show that the circuit suppresses common mode interference and serial mode interference from external switching power supplies, and improves the quality of infrared images; When there is an abnormal power supply as mentioned above, the protection circuit module will stop supplying power to the subsequent modules, protect the components of the subsequent modules from damage, and emit a light alarm^[2].

Moiré fringe has become one of the mainstream methods for high-precision distance measurement at present, and the accuracy of moiré fringe-based distance measurement can reach the nanometer level. However, due to the discrete sampling of moiré fringe images by camera and the non-integer sampling, spectral leakage occurs during Fourier transform, thereby affecting the measurement accuracy. By applying a 2D-windowing process to the moiré fringe, the spectral leakage can be effectively reduced and the accuracy of the moiré fringe phase demodulation improved. This paper conducted a simulation analysis on moiré fringes formed by three sets of gratings with different periods and obtained the most suitable window function for each of them. Finally, one set of the gratings was selected for height displacement measurement experiments on a wafer stage. The experimental results achieved a measurement accuracy better than 5nm.

Accurate extraction of laser fringe center line is a key step in online structured light vision measurement system. When there are too many pixels in the picture, the traditional Steger algorithm can not quickly extract the laser fringe center line. Therefore, a method of extracting the center of laser fringe based on Steger algorithm is proposed. In this method, firstly, the threshold method is used to segment the optical strip region, then the expansion algorithm is used to find the continuous optical fringe, and finally find the center of the light strip with Steger algorithm. Experimental results ompared with the classic Steger algorithm, the speed of optical strip extraction is improved.

We demonstrate a passively Q-switched Er:Yb:YAl₃(BO₃)₄ microchip laser with Co²⁺:MgAl₂O₄ as saturable absorber (SA). As the 976 nm pump light double passes the Er:Yb:YAl₃(BO₃)₄ crystal, stable Q-switched operation is obtained at a low threshold pump power of 1.1 W. In addition to this, with the help of sapphire crystal for heat dissipation, together with high initial transmission of SA and low transmission of output coupler, the microchip laser generates pulses at 1.5 μm with a maximum repetition rate of 205 kHz, pulse with of 9.8 ns and average output power of 1.04 W under CW pumping.

The laser point cloud is sparse and noisy, and the traditional iterative closest point (ICP) algorithm has poor robustness and long convergence time. In order to further improve the accuracy and robustness of point cloud registration, an iterative nearest point registration algorithm (FPFH-ICP) based on normal vector angle generation of Fast Point Feature Histograms (FPFH) is proposed. Firstly, the voxel grid filter and Statistical-Outlier-Remove filter are used for sampling, and the feature point normal vectors that meet the threshold conditions are screened to generate the point feature histogram. Then, the sample consensus initial aligment (SAC-IA) algorithm is used for initial registration, and the K-D tree accelerated iterative ICP algorithm is established to achieve fine registration. In this paper, multiple registration experiments are carried out on laser point cloud data with different characteristics in the two scenarios of straight and steering, and the results show that the improved FPFH-ICP can achieve efficient and robust registration for vehicle point clouds.

Grating coupler, one of the essential devices in silicon-based optical integrated chip, is still suffering with low coupling efficiency and small operation bandwidth. In this paper, we design and experimentally demonstrate a silicon nitride (Si₃N₄) grating coupler with high coupling efficiency and large bandwidth. Instead of using bottom distributed Bragg reflector, metal mirror or other complex designs, a bottom silicon grating reflector based on a 220 nm industrially standard silicon-on-insulator wafer is employed to improve coupling efficiency and simplify the fabrication processes. The interlayer coupler enables the light transmission between Si3N4 and Si waveguides. By optimizing structure parameters and apodizing the Si3N4 grating coupler, a high coupling efficiency of -2.37 dB and large 1-dB bandwidth of 53 nm are obtained.

Photonic processors have shown great potential to replace electronic processors due to the high parallelism, low latency, and low power consumption of light. The current direction of integrated optical computing research is focused on realizing vector matrix multiplication in light, which is also called photonic tensor processor. There are two main implementation schemes of photonic tensor processors: coherent and wavelength division multiplexing, and the latter is represented by the micro-ring resonator (MRR) weight bank. However, the MRR is highly sensitive to the manufacturing error, and it takes a long time to calibrate before used for calculation, which makes the realization of a large-scale MRR weight bank a challenge. We propose a novel architecture of wavelength-multiplexed photonic tensor processor based on Mach-Zehnder modulators (MZMs), which can reduce the time and power cost of device calibration We implement a 4×4 optical convolution operator based on the above architecture, which is used to solve the MNIST handwritten digit recognition problem. Prediction accuracy of 91.72% is achieved compared with the accuracy 97.58% achieved by a computer.

Organic photodetectors (OPDs) have attracted extensive attention due to their high flexibility, strong adaptability, lowcost, and compatibility with large-scale manufacturing technologies. However, achieving high specific detection (D*) and mechanical flexibility remains a challenge for flexible non-fullerene OPDs. A well-designed cathode interfacial layers (CILs) with good flexibility and stability is essential. Herein, a flexible CIL of tin ion-chelated polyethyleneimine ethoxylated (denoted as PEIE-Sn) is presented, which can effectively endow the devices with optimized cascade alignment and improved interface compatibility. The resulting flexible OPD exhibits an external quantum efficiency (EQE) of 59% and specific detectivity (D*) of 7.95*10¹² Jones (720 nm, -0.5 V) with a slight change after 1500 bending cycles. OPD has been validated through heart rate monitoring using the photoplethysmography (PPG) method, demonstrating its potential application in wearable devices.

The design of 21 mega-pixel mobile phone lens was introduced, which uses three aspherical optical plastic lenses, APL5514ML, OKP4HT, and E48R, and uses ZEMAX optical design software to design a mobile phone lens with up to 21 million pixels, the optical system has four aspherical optical plastic lenses, and another K9 filter is added to protect the CMOS sensor negative. The first and second lenses are negative and the third and fourth lenses are positive. The design results show that the modulation transfer function (MTF) of the central field of view at 1/2 Nesquith frequency is greater than 0.5, the MTF values at the full field of view are greater than 0.3, the aberration is less than 2 %, the relative illumination is greater than 50 %.

An on-chip optical power splitter is a crucial component for optical signal processing, widely used to implement Mach-Zehnder Interferometer, 1×2 switches, and optical arrays for various photonic integrated circuit (PIC) applications. In this paper, we present a tapered silicon waveguide power splitter with assisted subwavelength gratings (SWGs) that enhances coupling between waveguides and relaxes the critical dimensions requirement of the devices, with a taper tip width of 100 nm. The three-dimensional Finite-Difference-Time-Domain (3D-FDTD) simulation results demonstrate that the splitter has a low loss of only 0.1 dB over an ultra-broad wavelength range from 1200 nm to 1700 nm. The dependence of the performance on geometry variations, including tip width, gap spacing, waveguide width, and thickness of the device layer, is also investigated to illustrate the fabrication tolerance. The power splitter is also proved to be temperature-insensitive. With the advantages of low loss, ultra-broadband, fabrication-tolerant, temperature-insensitive, and relaxed critical dimensions (≥100 nm), the proposed power splitter is a promising practical building block for large-scale PICs.

Sulfate is an important anion in marine research and is closely associated with numerous marine phenomena. Laser Raman spectroscopy is a nondestructive, non-contact molecular fingerprint spectroscopy that can identify as well as quantify substances, and is suitable for the detection and quantification of substances in solution. In this paper, the Raman spectra of different concentrations of sodium sulfate solutions were measured under laboratory conditions and quantified by four methods: internal standard normalization method, multiple linear regression, random forest and XGBoost, respectively, to establish models and analyze the results. The results show that multiple linear regression, random forest, and XGBoost can improve the accuracy based on the internal standard normalization method, while random forest has the best results with a mean percentage error of 4.9867%, mean square error of 4.68932, and R ²= 0.98813, which proves the superiority of machine learning methods for quantitative analysis of Raman spectra based on target substances in seawater quantitative analysis of substances in seawater.

To well control the part temperature distribution and reduce the intra-layer heat accumulation in the selective laser melting (SLM) process, a three-dimensional finite element model was developed to simulate the effect of scan strategy (such as unidirectional, shuttle, block and ring) on the part temperature field in SLM process. The model considered the physical properties of the AlSi10Mg material such as density, specific heat capacity and thermal conductivity. The Gaussian heat source was normally employed to simulate the heating, melting, solidifying and cooling process during the manufacturing process. Results show the relative error between the measured single-pass melt pool width and simulated result is within 4.2 %. The ring scanning is optimal due to the uniform temperature distribution and smaller temperature gradient. The proposed model can provide powerful guide for the selection of scanning strategy in the real manufacturing of continuous SLM process.

In this paper, rod-like Bi₂S₃ nanoparticles have been synthesized using gelatin as a capping agent by a one-pot solvothermal method. Furthermore, some samples were further characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Raman spectroscopy, and other means. The results demonstrate that the Bi2S3 nanoparticles are rod-like with good purity. Furthermore, the prepared Bi₂S₃ nanostructures show high efficiency in the photodegradation of rhodamine B.

The factors affecting the acceleration process of interaction between double plasma targets and the ultraintense linearly polarized laser pulse has been studied in this work. The results show that extra electrons provided by the pre-target play important roles in enhancing the longitudinal bipolar field and better confining of the protons from the main-target. Besides, there exists great difference between s- and p-polarizations of the laser pulse for distinguished transverse effects. By contrast to the case of circularly polarized laser pulse, higher areal density ratio of pre-target to main-target is needed to achieve efficient plasma block acceleration driven by the linearly polarized one. Finally, monoenergetic proton beam has been obtained via double targets driven by a linearly polarized laser pulse, which has better collimation, monochromaticity and stability, as well as higher energy conversion efficiency.

Carbon fiber reinforced polymer is a new type of high-quality material, which is used in various fields such as aerospace. Due to its processing characteristics, femtosecond laser has become its new high-quality processing method. In this paper, femtosecond laser pump-probe technology is used to study the ablation of CFRP by femtosecond laser, and try to explore the femtosecond laser processing mechanism of CFRP. In this paper, continuous images of femtosecond laser ablation CFRP materials were collected under ultra-fast action time. The experimental results found that the reflection of a single epoxy resin material first increased and then decreased under femtosecond laser ablation; Under the second laser ablation, the reflection first increases and then decreases, but the peak time delay is relatively delayed compared with the resin.

We propose an ultra-broadband, compact size and low loss 3-dB adiabatic subwavelength grating-based power splitter based on the silicon-on-insulator platform. Simulation results show that our proposed device has an operating bandwidth of 250 nm, covering the wavelength range from 1400 to 1650 nm, while the device size is reduced to 11 μm and the excess loss is as low as 0.22 dB. Compatible with mature CMOS process, our proposed subwavelength grating-based power splitter shows excellent potential for large-scale photonic integrated circuits.

With the continuous progress of the national economy and of science and technology, gold plays an increasingly important role in social production and life. The existing detection technology for gold has the disadvantages of heavy pollution and high cost. As an emerging material detection technology, laser-induced breakdown spectroscopy has many advantages, such as low pollution, low cost, rapid detection, and online detection. In this paper, nanosecond lasers and spectrometers are used as the main tools to study the application of laser-induced breakdown spectroscopy in the field of gold element detection. Experiments have found that, under the action of a nanosecond laser with a wavelength of 1064nm, the plasma spectrum of gold has a sharp characteristic spectrum near 242.8nm, which points out the direction for the laser-induced breakdown spectroscopy technology to be used in gold mine detection.

Genetic engineering should be achieved by means of gene transfection methods, but traditional gene transfection technology has many disadvantages such as high cell lethality, easy introduction of pollutants, high cost, etc., while femtosecond laser has ultra-short single pulse time, ultra-high peak power, and small ablation area, which is in line with the requirements of cell transfection. In this paper, based on gene transfection and regulation of cell expression, combined with the advantages of femtosecond laser ultra-fast and super strong, femtosecond laser transfection was used to transfect protein-sensitized functional proteins into embryonic cell lines, and the influence of various processing parameters on transfection efficiency results was studied, high transfection efficiency and better transfection expression results were obtained, high-precision and efficient transfection results were realized, and the mechanism of laser-cell interaction was established, so as to realize laser precision regulation of cell transfection.

In this article, a fiber-solid hybrid amplification picosecond laser system is developed. The maximum single pulse energy of the fiber seed source can exceed 50 nJ and the beam quality factor M² is less than 1.10. After two-stage traveling-wave amplifiers, the final average power of 23.6 W was obtained, corresponding to the maximum single pulse energy of 118 μJ with a repetition rate of 200 kHz. The research results of this article can provide an effective reference for the implementation of a higher-power Nd: YVO₄ laser system.

An erbium-doped fiber laser based on nonlinear polarization rotation (NPR) mode-locking is proposed. On account of the multi-mode interference filtering effect introduced by the laser cavity multi-mode fiber, by adjusting the cavity polarization controllers, the laser generates dual-wavelengths of 1533.48 nm/1547.61 nm, 1549.16 nm/1561.94 nm, 1533.14 nm/1562.96 nm, and triple-wavelengths of 1533.43 nm, 1548.46 nm and 1562.68 nm, corresponding to 388.95 kHz, 388.93 kHz and 388.91 kHz, respectively. The compact structure of the system has potential applications in spectroscopy, optical communication, optical sensing and other fields.

We demonstrated a 3.8 kW-level all-fiberized high-brightness laser with the structure of MOPA (master oscillator power amplification). The maximum output power is ~3894 W with the SRS (stimulated Raman scattering) intensity 10 dB below and ~3812 W with the SRS intensity 20 dB below. The spectrum has a central wavelength of 1080 nm with an FWHM (full width at half-maximum) bandwidth of ~2.2 nm. The slope efficiency of the fiber amplifier with respect to the pump power is ~81%. With a 25-μm-core ytterbium-doped gain fiber of the amplifier and 30-μm-core output fiber, the laser can keep a high beam quality (M² ) which is estimated to be about 2.6 below.

Using ytterbium doped single-clad/double-clad fiber amplifiers, different amplification experiments were conducted on narrow pulse width picosecond light, and the influence of self-phase modulation on pulse frequency domain characteristics during amplification was analyzed. A self developed picosecond oscillator based on semiconductor saturable absorber mirror (SESAM) mode locking is used to directly enter the main amplifier device. The oscillator has a pulse width of 6.8 ps, a repetition rate of 20.76 MHz, and a center wavelength of 1064.3 nm. After amplification, the maximum output power is 315 mW, with an energy of about 15 nJ. The phenomenon of spectral changes caused by selfphase modulation of picosecond pulsed light during amplification is explored. When the output pulse optical power is about 200 mW and the pulse energy is about 10 nJ, and the injection power is 39.4 mW, 134 mW, 229.2 mW, and 326.8 mW, respectively, the corresponding spectral widths are 0.187 nm, 0.522 nm, 0.53 nm, and 0.588 nm, respectively. Experimental research shows that under the same output pulse energy conditions, the smaller the injected optical power, the better the output pulse spectral morphology. As the injected optical power decreases, the effect of pulse shape on self-phase modulation in fiber lasers decreases.

A frequency-tunable Q-switched laser operation at 1064 nm pumped by a wavelength-locked 878 nm semiconductor diode was reported. Under CW operation mode, the maximum output power of 30.5 W was obtained while the pumping power was 55.9 W, and the light-light conversion efficiency was 54.56 %; While in the Q-switching operation mode, the maximum output power of 24.93 W was obtained when the pumping power was 53.05 W, and the light-light conversion efficiency was 46.54 %. Provides stable operation in Q-switching mode between 60 kHz and 300 kHz repetition frequency with a pulse width range of 22.5 ns to 24 ns. The laser with beam quality M ² _x=1.21 and M² _y=1.33 was obtained.

Femtosecond laser was used to fabricate antireflective holes on the surface of ZnS. The micro hole structures were formed by different single laser pulse energy. It was found that with the increase of single pulse energy, the infrared transmittance of ZnS surface decreased. Under optimal parameters (single pulse energy of 0.1 μJ), the average infrared transmittance of ZnS increased to over 79%, 4% improvement compared to the untreated ZnS. The light transmission in planar ZnS and micro hole structures ZnS was simulated by FDTD, which theoretically verified the antireflection property of micro hole structures.

In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Two paths, namely straight and sine are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined, along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding sine path. Notably, numerical simulation results are validated through experimental data, and sine oscillating laser welding significantly reduced weld seam porosity in the welding of Ti-Al dissimilar alloys. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.

Silicon carbide (SiC) fiber-reinforced SiC-matrix (SiC/SiC) composite has a wide range of applications in the aerospace field. However, SiC/SiC composite is typical difficult-to-machine materials due to their non-homogeneous and anisotropic properties, and traditional manufacturing processes cannot meet their processing requirements in aerospace applications. Femtosecond laser processing technology is expected to become the preferred choice to meet this demand, due to their ultrashort irradiation periods and ultrahigh intensities. In this study, the micro-grooving processing on the surface of SiC/SiC composites by femtosecond laser is investigated, and the effects of laser power, scanning speed and scanning frequency on the surface morphology of SiC/SiC composites are investigated. The results show that there are recast layers in the ablation zone and powdery substances in the processing zone during the laser ablation process of SiC/SiC composite. The width and depth of the micro-grooves increase with the increase of laser power and scanning times. When the ablation power is low and the scanning times are few, the grooves are non-uniformly distributed with sawtooth structure. When the ablation power is high and the scanning speed is low, the grooves are serrated. Properly increasing the scanning speed and scanning times can reduce the sawtooth structure and improve the surface quality of the ablated area. This proposed method can achieve good morphology of SiC/SiC and is expected to be applied to industrial processing of SiC/SiC.

This thesis uses liquid-phase femtosecond laser processing of zinc flakes in anhydrous ethanol. The results show that a micro-nano composite structure is formed; and the period of the composite structure is increased nearly 10 times compared with that fabricated in air. The direction of period structure is distributed at an acute angle to the processing direction and not directly related to the polarization direction. The formation direction of the micro-pores is the same as that of the vortex flow in the liquid.

A single-photon avalanche photodiode (SPAD) is a type of photodiode that operates using the avalanche effect to detect light down to the single photon level. When SPAD detects photons, it generates a massive avalanche of charges which can damage the diode. The quenching circuit prevents these problems by quickly limiting the current flowing through the diode and reducing the avalanche effect. This paper designs an improved SPAD active quenching circuit model. This model introduces an avalanche self-sustaining module to increase the quenching time of SPAD, so that the reverse bias voltage can be well quenched. The simulation results of the improved circuit model and the traditional quenching circuit model are compared in detail by using Cadence PSpice. Set the photon incident time to 500ps, and the reverse bias voltage to 73V. Simulation results show that the improved model can be quenched to 70.051V, unfortunately, the traditional model can only be quenched to 72.848V. Thus, the improved active quenching equivalent circuit model has short recovery time and better quenching effect. It can be used to simulate SPADs with high temporal resolution.

Escherichia coli O157:H7 (E. coli O157:H7) is a public health hazard for enteric pathogens. Thus, it is essential to detect E. coli with high sensitivity. In this study, a dual signal enhancement fiber-optic surface plasmon resonance (SPR) sensor is proposed to enhance the sensitivity. The sensor surface was modified by graphene oxide (GO) as the signal enhancement layer and the Au nanoparticles (AuNPs) were used for secondary signal amplification. It can significantly improve the sensitivity by four orders of magnitude compared with the traditional fiber-optic SPR sensor. The limit of detection (LOD) for E. coli O157: H7 was 142 CFU/mL and the detection range was 10³ - 10⁷ CFU/mL. The developed sensor has high sensitivity and specificity. Therefore, the sensor may be a potential tool for detecting other biological pathogens.

We have designed and constructed a femtosecond laser two-photon polymerization (TPP) system and explored its processing capabilities through experiments. By performing single-point processing experiments with varying laser energy, the energy range for photoresist polymerization was determined. By adjusting the scanning speed and laser energy, the minimum achievable line width of the fabrication system was obtained. What’s more, in combination with the precision of the translation stage used, suitable laser energy and scanning speed were selected to fabricate structures resembling the ruins of the Parthenon, which demonstrates the excellent processing capabilities of our fabrication system.

Microring resonators (MRRs) are widely used in optical filters due to their compact size, high Q, and narrow linewidth. However, traditional MRR-based high sensitivity sensors suffer from narrow free spectral range (FSR), which limits the number of channels for detecting substances and causes interference with the identification of the center wavelength when the refractive index of analytes changes significantly. In this paper, we propose an ultra-large FSR and high sensitivity filter utilizing subwavelength grating slot microring resonator with inner silicon blocks with different widths, achieving FSR of 95.5 nm and refractive index sensitivity of 743 nm/RIU. And a lab-on-chip system comprised of eight channels-based filters is presented, promoting the development of silicon photonics in the detecting resolution of small refractive index changes of analytes to 3.60×10^-4 RIU and multiple analytes simultaneously.

Titanium alloy has been widely used in aerospace fields due to its high strength and good corrosion resistance. However, the machining of titanium alloy faces many difficulties, such as high cutting force, serious tool wear, and poor machining accuracy. Femtosecond laser has the characteristics of ultra-fast and ultra-strong, which can remove materials on titanium alloy without contact, and does not cause deformation and heat-affected zone. This paper designed a fs-laser turning module, which could be installed on a CNC lathe for precision turning of titanium alloy parts. In addition, modal analysis of the laser turning module was conducted to verify that the laser turning module did not resonate with the CNC lathe, which would affect the machining accuracy.

Due to the characteristics of ultrashort pulse duration and ultrahigh peak power of femtosecond laser, it is widely used in manufacturing industry. To monitor ultrafast dynamics during femtosecond laser-material interactions, ultrafast pumpprobe spectroscopy with high spatiotemporal resolution has been used. However, single-crystalline silicon ablation combined with ultrafast electron dynamics and high spatial resolution is still understudied. In this study, we systematically investigated the process of femtosecond laser irradiation of single-crystalline silicon, revealing the mechanism of femtosecond laser processing of periodic structures. The formation of periodic ripples is explained by two mechanisms: direct interference of surface plasmons and incident laser, and grating-assisted coupling of surface plasmons with laser.

Energy efficiency and integration scale are two of the major challenges of current optical computing chips. To solve these problems, we propose for the first time a special multimode interference(MMI) and dynamic monitoring idea. The research of the device is based on finite element analysis. There is a nano-opto-electro-mechanical(NOEM) ratio controller in the upper left of the multimode waveguide. Most of the time, the device is in static mode with power-splitting-ratio(PSR) close to 0:100. The research shows that once the controller is started, the device enters dynamic mode with a PSR bigger than 5:95. The PSR is less than 0.36:99.64 in a selected static mode and up to 8.35:91.65 in dynamic mode. The change of PSR in dynamic mode is realized by adjusting distance between NOEM module and multimode waveguide. The footprint of the multimode waveguide is only 1.54×3.63μm² . Its minimum insertion loss(IL) is less than 0.2dB and has good process tolerance characteristics. The energy consumption of discontinuous monitoring based on the MMI is significantly lower than that of continuous monitoring. It is estimated that when duty cycle of the periodic monitoring module is 0.1 and 0.01, its monitoring energy consumption can be reduced by 70% and 97%, respectively. The MMI is expected to greatly promote the development of optical computing chips.

We investigated the structures and energies of three low-index stoichiometric surfaces of Cu₂O using first-principles. A new scheme that utilizes correction surface energies more accurate than the average surface energy was employed to calculate the surface energies. Both surface energy schemes revealed that the surface energy magnitude follows the order of (111) < (100) < (001). The Wulff indicated that the percentages of the (001), (100), and (111) surfaces in the total crystal surface area were 25%, 25%, and 50%, respectively. These findings will contribute to the design of more efficient photocatalysts.

The ineffectiveness of powder morphology of crystal materials for laser polarization has reached a consensus in almost all steady-state experiments. However, in-depth understanding about their anisotropic behavior in ultrafast carrier dynamics is still lacking. Here we systematically explore the polarization response of MAPbI3 powder to ultrafast laser based on two-color pump-probe transmission technology. The isotropy of pump polarization and the anisotropy of probe polarization reveal the related mechanism of the interaction between ultrafast laser polarization and powder materials. It provides insight into the ultrafast photophysical process of MAPbI3 powder and helps to develop polarization-sensitive and ultrafast-responsive optoelectronic devices.

The mismatch between spectral responses of each channel of the tristimulus colorimeter and the tristimulus value of the CIE1931-XYZ spectrum will cause systematic errors in chromaticity and luminance measurements. In the measurement of emissive displays, such as LED, OLED or micro-LED displays, spectral colorimeters are often applied to correct results measured by tristimulus colorimeters. However, the accuracy and repeatability of corrected results are affected by random noise and sampling difference. To overcome the both impacts, a spectrum-enhanced algorithm based on multi-sub-pixel sampling is introduced to correct tristimulus colorimeters. Firstly, the principle of the algorithm is presented. Secondly, simulation is conducted to verify that the accuracy and repeatability of chromaticity and luminance improve with the increase of the quantity of sub-pixels sampled. Comparative simulation and experiment are conducted for further verification in condition of sampling 8 sub-pixels and sampling one sub-pixel. The average and standard deviation of residual errors in condition of multi-sub-pixel sampling is respectively 20% and more than 70% lower than those in condition of single sub-pixel sampling. The spectrum-enhanced algorithm based on multi-sub-pixel sampling presented can effectively correct tristimulus colorimeters for high-precision chromaticity and luminance measurement of emissive displays.

In this paper, we focus on the problem of the visible images and the infrared images fusion detection. Aiming at the incomplete target information obtained by the single wave band target detection algorithm, an improved DenseFuse pixel-level fusion detection model CLHE-DenseFuse-Mask R-CNN is designed to fuse the information of the visible images and the infrared images. In order to solve the problem of the information loss caused by a single fusion method, a multi-source target detection model Mask R-CNN based on the pixel-level fusion and the decision-level fusion MF-Mask R-CNN is proposed. The experimental results show that the multi-fusion target detection model MF-Mask R-CNN significantly improves the detection accuracy of the targets

Super-resolution optical fluctuation imaging (SOFI) uses the advantages of computational post-processing to solve the super-resolution problem under high labeling density. Higher-order SOFI requires sufficient fluorescence fluctuation information to reduce artifacts in reconstructed images. However, the length of image sequence is limited for a certain kind of fluorophores, such as the inherent lifetime. In this research, we proposed a method to enhance image quality using double-color acquisitions and then coupling them into sequences. The theoretical basis and the working principle of this method will be explained. Simulations and limitations analysis between typical acquisition and this method will also be given. Simulations demonstrated that this method can improve the overall image quality by about 31.58 % in the 2^nd order SOFI and 56.26 % in the 4^th order SOFI.

A distributed optical fiber strain sensing under ultra-low temperature based on Rayleigh Backscattering light was realized in this paper. An auto correlation demodulation technique was used to improve the measurement accuracy. The optical fiber’s displacement caused by ultra-low temperature environment was corrected during the auto correlation operation. A temperature compensation Technology based on Fiber Bragg Grating Sensing was proposed, which could effectively compensate the impact of thermal expansion of the structure on the distributed optical fiber. The technique can adapt to the measuring environment with large temperature changes, and significantly improve the accuracy of strain measurement.

With the rapid development of UAV technology, the jamming method of UAV has attracted more and more attention from various countries, which makes the jamming model of laser on UAV detector have been studied deeply.By analyzing the working mode of UAV detector, an equivalent experimental system of laser irradiation optical detector was established in the laboratory environment. The corresponding relationship between pixel saturation and power of detector and the irradiation effect of single beam and double beam laser on detector under different angles were analyzed experimentally. The results show that the saturation spot size of the detector has an approximate linear relationship with the laser incident power, and different saturation interference laser power can be obtained according to the different properties of the sensor. Through the analysis of the established physical model that the incoming power of a single laser varies with the detection Angle, it shows that a single laser only has a certain irradiation effect on the detector below the deflection Angle of 50°. Symmetrical dual laser beam can improve the damage effect of optical detector.

In this paper, an indoor segmented mirror co-focus and co-phasing experiment system is constructed in order to successfully identify and correct co-phasing errors in the segmented telescope. The Golay-7 segmented mirror's piston error and tilt & tip error are detected by this experimental system's pyramid wavefront sensor. The control system is used to drive the closed-loop correction of the active segmented mirror. The results of the experiments demonstrate that this method is capable of achieving fine co-focus and co-phasing of the Golay-7 segmented mirror. A segmented mirror system can approach imaging towards the diffraction limit.

Using the optical vortex beams (OVBs) can further improve the communication rate and spectrum utilization of the conventional space optical communication systems. In order to suppress the atmospheric turbulence effects in the space OVBs communication links, as well as to make the communication links simpler. We introduced the pin-like optical vortex beams (POVBs) that can dynamically self-focus during the free-space propagation. The POVBs have ability to counteract diffraction effects and atmospheric turbulence effects, and can maintain stable propagation with constant shape over long distances in the free-space. We theoretically analyzed the POVBs and experimentally demonstrated their stable propagation performance in the simulated atmospheric turbulence.

To improve the security and efficiency of the image message transmission. This paper propose an optical image encryption scheme based on random phase mask and four-step phase shift digital holography. In the process of image encryption, the low frequency sub-band of the original images are superimposed by wavelet transform to increase the encryption efficiency. In this paper, Henon mapping generates two random phase masks. The initial values and control parameters of Henon mapping can be used as the main keys. The use of random phase mask makes the transmission and storage of the keys of sender and receiver more convenient. Moreover, the wavelength and diffraction distance are also used as the keys, which can enhance the security of encryption. With the help of random phase masks and four-step phase-shifting digital holography, the original image is encrypted into four cipher holograms. The simulation results show that the encryption algorithm proposed in this paper can reconstruct high-quality decrypted images and effectively resist various noise attacks

This paper applies Fresnel diffraction theory to analyze the phenomenon of multiple-beam interference in thin waveguides, and subsequently carries out simulation experiments. And further investigates the correlation between the angular deviation triggered by interference and the thickness of the waveguide. To be specific, the paper delves into the detailed analysis of this correlation, thus highlighting the significance of this research.

This paper presents a novel approach that utilizes airborne LiDAR point cloud data to reconstruct the growth of individual eucalyptus trees in a forest. Firstly, the point cloud data is preprocessed using specialized software to separate the land and eucalyptus forest vegetation canopy surfaces. Next, a single tree feature matching algorithm is employed to isolate a single eucalyptus tree. The single tree forest is then segmented on an elevation projection image, which enables accurate calculation of the plane coordinates, tree height, and crown diameter, ultimately resulting in the position modeling of each tree. Using the single tree model, the biomass of each tree is estimated through its growth equation. This method provides a visual simulation of the laser point clouds of single tree morphology to the overall forest, which allows for the estimation of the aboveground biomass of eucalyptus forests. The research results are expected to provide technical support for estimating the carbon storage of eucalyptus forests in the region. Overall, this approach offers a valuable tool for forest management and carbon accounting, which can help to promote sustainable forestry practices.

Silicon photonics enables large-scale integration of Frequency Modulated Continuous Wave (FMCW) Light Detection and Ranging (LiDAR) system on silicon on insulator (SOI) substrate. In this paper, we set up an FMCW LiDAR system for a chip-scale coherent receiver chip based on a 3 µm SOI platform which has the advantages of low waveguide loss and high process tolerance. An iterative learning pre-distortion method is used for linear frequency sweep. With the home-built FMCW LiDAR system, we have achieved a detection range of 160 m with an accuracy of 0.3 m which pave the way for miniaturized LiDAR used for autonomous driving.

To enhance the accuracy, efficiency, and safety of large-aperture non-spherical optical components, we have proposed a novel strategy for path planning and detection, which uses a non-contact optical probe suitable for spindle-rotating contourimeters. Our strategy leverages the contourimeter's working principle and the structural characteristics of the surface, transforming the three-dimensional collision problem into a two-dimensional detection space. To accomplish this, we first decompose the cross-section of the workpiece into a quadtree space and establish oriented bounding boxes for each sub-node. We then use the separation axis principle to ensure motion safety between the positions of the test points. Next, we utilize the ant colony optimization algorithm to plan the detection path and generate an interference-free scanning route that ensures safety during the detection process. Overall, our path-planning strategy significantly improves detection efficiency, while ensuring that the detection process is conducted safely. By combining these methods, we created a robust and effective approach to detecting large-aperture non-spherical optical components.

In order to achieve effective modulation, researchers have studied various doping profiles within silicon modulators, but optimization has so far mainly been carried out in the cross-section or solely in the propagation direction. Generating 3D doping profile can add more optimizing dimensions to the modulator design. This work proposes a modulator based on U-shaped and L-shaped junctions by the 3D effective Monte-Carlo method. The simulation results show that the modulation efficiency is 0.67 V·cm, and the loss is 25.7 dB/cm, with the bandwidth more than 36.3 GHz. This work demonstrates the benefits of 3D modulator design as the direction of light propagation is utilized to transport carriers, and provides a modulator solution for high-speed datacom.

One of the crucial tools for measuring the extensive atmospheric showers brought on by cosmic rays is the imaging atmospheric Cherenkov telescope. There are hundreds to tens of thousands of distinct photomultiplier tube arrays or pixels inside each imaging atmospheric Cherenkov telescope. The size of the array spans the area corresponding to each telescope’s field of view. This paper discusses the differences between the square and stagger arrangement of the photomultiplier array along with compares the photon collection capabilities of the two arrangements. The results reveal that the experiment works better using a square arrangement of the photomultiplier array.

The advancement of measurement equipment has enabled the extension of measurement applications from physical samples to the vast and scattered point cloud data. This expansion has fostered the growth of reverse engineering technology, which is widely used in the manufacturing industry. Reverse engineering involves data acquisition and surface reconstruction, where normal vector control is a more straightforward approach than B-spline control polygons for surface design and modification. This study proposed a complex surface reconstruction algorithm incorporating normal vector constraints for reconstructing scattered point clouds. Physical experiments were conducted to demonstrate the feasibility of the proposed method, and the results showed that it has significant potential for detecting complex surfaces.

In recent years, the increasingly serious problem of marine pollution has raised high concern about environmental issues among people, which in turn has promoted rapid development of marine pollution detection technology. UV fullspectrum analysis is a nitrate detection method based on characteristics such as no reagents required, convenient and fast, and high detection accuracy. This article takes nitrate standard solution prepared with potassium nitrate as the experimental object, collects UV full-spectrum from 0 to 7mg/L standard solutions, uses the Savitzky-Golay (SG) smoothing algorithm to remove noise from the original nitrate full-spectrum data, processes the UV full-spectrum data using principal component analysis (PCA) algorithm, extracts characteristic bands, and uses BP neural network modeling for the screened bands. The results show that within the spectral range of 201-207nm, the prediction model achieves the highest coefficient of determination, with an R² of 0.99997, and the smallest root mean square error, with an RMSE of 0.11149, and all performance indicators are superior to those of the UV full-spectrum modeling method.

Contemporary battery management systems (BMS) rely on monitoring external parameters such as voltage and current to ensure that the battery operates safely and has the required performance, often resulting in overdesign and inefficient capacity usage. Embedded sensors can be used for internal battery condition monitoring to provide accurate operating status information and state of charge. This paper presents an embedded optical sensing method using a tiny fiber optic sensor implanted inside a lead-acid battery. Under the premise of not affecting the performance of the battery, the refractive index sensitive characteristics of the inclined grating are used to monitor and feedback the electrolyte concentration in the process of battery discharge in real time. The tilted fiber Bragg grating(TFBG) sensor can provide on-line feedback of discharge through transmission spectrum. And it can also realize the high sensitivity online monitoring of the discharge quantity of lead-acid battery, which provides a convenient method for researchers and engineers to manage the battery.

At high angular velocity, the signal-to-noise ratio(SNR) of star image may become very low due to star point tailing, which leads to the decline of the star extraction rate. To solve this problem, an adaptive star extraction algorithm is proposed in this paper. Firstly, the star image is divided into several blocks, and the adaptive global threshold method is used in each block to get the gray extremum of each block. Then, the weight matrix of the star under the current angular velocity is obtained adaptively by Kalman filter. For the selected extreme pixel, the background threshold of the pixel is obtained by using the maximum background estimation method according to the calculated weight matrix. Finally, region growth is carried out in the eight neighborhood of the current pixel until all the star pixels are extracted. The experimental results show that this algorithm can extract stars in images taken at high angular velocity, and the extraction rate is higher than that of the traditional scanning method, which proves the algorithm is effective and has good robustness.

The dielectric filter is a commonly used optical filter, benefiting from its low production cost and compact size. While the bandwidth of the dielectric filters made by traditional fabrication technique can hardly reach sub-nanometer. Here, we present a method for fabricating a sub-nanometer dielectric filter using the Fabry-Pérot (FP) cavity. This FP dielectric filter features a full width at half maximum (FWHM) bandwidth of ~0.18 nm, a free spectral range (FSR) of 11.23 nm and a peak transmittance of over 80%.

In order to overcome the problem that traditional phase shifting interferometry requires hardware equipment with high stability, a phase extraction method for grating projection interferograms with two-step random phase shifting based on the improved Gram–Schmidt orthonormalization technology is proposed. Firstly, the background of the two-frame grating projection interferograms obtained by random phase shifting is filtered by Gaussian high-pass filter. Then, the phase shift value is obtained by the relation between the norms of two vectors. The phase distribution of the interferogram is extracted by a two-step phase shifting algorithm based on the arctangent function. In addition, the grating projection measurement system is designed, and the real experiments results show that compared with GS algorithm, the proposed method can obtain the phase shift value, and has obvious advantages in accuracy and calculation speed.

In recent years, researchers have proposed many image fusion methods based on convolutional autoencoder structure, which can make the feature map extracted by convolutional neural network more suitable for image fusion task through specific network structure, specially designed functional modules and loss functions, and achieve satisfactory results. However, these methods all use feature maps of different scales for direct fusion, and usually the information between different parts of an image is related. If the feature map is directly fused, only the local features of the image are used, while the global information of the image is ignored. In order to improve this defect, this paper will first introduce the Transformer model with multi-head self-attention as the core, how Transformer introduced into the image processing task, combined with the previous autoencoder fusion framework, propose an image fusion model based on attention feature, and design and conduct comparative experiments. Experimental results show that this method can effectively obtain the global features of the image, so as to further improve the quality of infrared and visible image fusion.

The trend of modern radar signals towards multi format, multi frequency band, and large bandwidth has posed greater challenges to radar signal detection in electronic warfare, requiring receivers to have large instantaneous bandwidth, wide spectral coverage and high-frequency spectral resolution capabilities. Microwave photon technology, due to its advantages of low loss, large bandwidth, resistance to electromagnetic interference, and simple equipment structure, is matched with the demand for ultra wideband channelized reception. This article designs a parallel reconfigurable channelized reception scheme for high-frequency and broadband signals and conducts simulation verification. A coherent dual optical comb with 30 comb teeth is generated based on a cascaded electro-optic modulator, and a dual parallel Mach-Zehnder modulator is used to broadcast the broadband signals and frequency shifting of optical combs to achieve channel division of 17 channels. Finally, a filter was used to filter out the signal from a single free spectral region of the optical comb for down conversion, achieving information extraction of high-frequency broadband signals with a bandwidth smaller than the free spectral range of the optical frequency comb using a small free spectral region optical frequency comb.

High-power optical enhancement cavity is widely used in precision optical experiments and metrology. The absorption of cavity mirrors leads to the distortions of the mirror surface. Thermal deformation in a high-power optical enhancement cavity leads to a decrease in cavity gain due to alterations in the Gouy phase. In this paper, we establish the analytical relationship between mirror deformation and cavity gain by using the Winkler deformation model. The deformation exhibits an inverse proportionality to the square of the finesse. This significant result confirms the great sensitivity of gain to deformation in a cavity with high finesse.

As the primary tool for studying cells and biological tissues, micro-imaging technology has significantly promoted the bio-medical development. The microscopic ghost imaging system is designed to meet the diverse needs of microscopy imaging. In this method, the original optical path of a research-grade upright fluorescence microscope was modified to be an optical path of ghost imaging. Three different matrixes were adopted as the preset pattern of the digital micromirror device. The experimental results demonstrate that the gold matrix can obtain a relatively perfect result under weak and unstable lighting conditions. This method is expected to promote the application of ghost imaging technology in microscopy imaging of cells and biological tissues.

The establishment of satellite-to-ground high-speed laser communication link needs to maintain high speed, high precision and high sensitivity, but the beacon signal becomes weaker following the ultra-long-distance transmission between the sending end and receiving end. Considering the problem of rapid attenuation of free space communication optical signals in the future development of high-orbit inter-satellite and inter-satellite transmission, this paper proposes a method of dynamic range compression modulation of coded aperture to improve the accuracy, rate and sensitivity of optical signal imaging acquisition in high-speed laser communication links. Further combined with coordinate system correction, highspeed, high-sensitivity and high-precision satellite-to-ground laser tracking and communication link maintenance can be achieved. Finally, the feasibility of dynamic range compression modulation of coded aperture for optical communication measurement is verified by the design and simulation of laser communication beacon optical modulation matrix, which provides the possibility for its wide application.

This paper designs a binocular three-dimensional (3D) display based on pixelated nanograting matrix. A view modulator covered with the nanograting matrix forms a specific view distribution according to the binocular position in space. Furthermore, we introduce the concept of super multi-view display to resolve the vergence-accommodation conflict (VAC). In the experiment, we combine the LCD screen and the view modulator pixel by pixel. Then a binocular super multi-view 3D display prototype is constructed with collimation backlight. The experiment demonstrates that this scheme can present stereoscopic images with correct depth cues.

In this paper, a kind of transparent 3D static display consisting of a flat glass waveguide and single layer gratings is proposed. The gratings are shaped into various patterns and designed pixel by pixel to provide correct parallax images. Incident light from the edge of the flat glass can only be extracted from the patterned area and projected to designed views. The prototype shows the advantage of wide field of view (60°), small angular separation (5°) and high transmission (<60%). Virtual 3D objects blend well with the real scene. Potential applications include window display and advertisements

Metasurfaces possess the ability to manipulate the wavefront of electromagnetic waves, but the majority of them are limited to single transmission or reflection mode without altering their structure. To address this limitation, we proposed a switchable terahertz metasurface for wavefront manipulation. By capitalizing on the phase transition properties of vanadium dioxide (its conductivity changes with temperature), the metasurface can work in the transmission or reflection mode controlled by temperature. Additionally, we designed 8 encoding elements to achieve phase gradient by changing the shape of the unit element. Finally, we arranged the encoding unit element to create a transmission and reflection mode switching optical device for beam steering and focusing.

A novel noise-robust hyperspectral anomaly detector based on relative total variation collaborative representation is proposed to settle the problem of low detection probability of collaborative representation detector under the condition of noisy hyperspectral image or large and irregular anomaly. The relative total variation method is employed to preprocess hyperspectral image and to obtain the pure structure information of hyperspectral image, which features lower intra-class difference and higher inter-class difference. Subsequently, the collaborative representation detector can be carried out, effectively alleviating the abnormal contamination of local background. Superior anomaly detection performance is obtained by the proposed algorithm, and the dependent of anomaly detection accuracy on the size of double-windows is greatly reduced.

Purpose: Development of subcutaneous LED vein display device, which is convenient for infusion at night or in dark light and in emergency, to improve the success rate of venipuncture. Method: The adult model uses red light and plant red, and the children model uses orange light and amber LED dual light source design, the lamp beads are connected in axisymmetric form, and automatic sensing is realized through the infrared sensor module. Result: During venipuncture, the infrared sensor module drives the LED to light up when the palm is placed above the display to assist the medical staff in finding blood vessels. Conclusion: The display device can clearly display the position of blood vessels without projecting the subcutaneous blood vessels onto the skin surface in situ, which improves the probability of successful venipuncture once.

The mainstream spectrum analysis algorithms include FFT spectrum estimation and Welch spectrum estimation, both of which have lower spectral resolution and depend on the number of sampling points. This article introduces a refinement algorithm based on FFT spectrum estimation, which moves the center frequency f_o of the refinement range to the zero position of the spectrum graph, effectively suppressing spectrum aliasing and fence effects. After using a low-pass filter for filtering and resampling, the local sampling frequency is increased from the original 1000Hz to 5000Hz, known as ZoomTTT refinement. Then, energy center correction with a Hanning window is used to further improve the speed measurement accuracy. Compared to the 98% universal accuracy of Welch spectrum estimation analysis, the improved speed measurement accuracy reaches over 99.5% and the error fluctuation is smaller.

By coherently superimposing two chirped vortex pulses with frequency differences and conjugate topological charges, a tunable ultrafast rotating optical field is generated. The interfering device is an asymmetric Michelson interferometer. There are three parameters to regulate the ultrafast rotating optical field: the topological charge difference ∆l; the chirp constant C; the optical path difference of the two interference pulses Δt. The experiment obtained the dynamic image of the rotating optical field by the nonlinear sampling ultrafast imaging, the rotational angular velocity measured in the experiment is 2.368 Trad/s, which are in good agreement with the theoretical calculations. Two nonlinear imaging mechanisms, sum-frequency generation (SFG) and optical parametric amplification (OPA), are applied for ultrafast nonlinear sampling. The results show that at the same rotational angular velocity of the rotating optical field, the image quality of OPA imaging is better than that of SFG imaging. These rotation optical fields at Trad/s level have important potential applications in particle acceleration, vortex THz wave generation, laser fine machine, etc.