In order to effectively reduce the surface state density of GaAs and obtain a stable high-performance passivation film, the GaAs surface was passivated by using the solution of octadecanethiol in different solvents. The effects of solvent polarity on passivated GaAs surface by octadecyl mercaptan solution were researched by X-ray diffractometry, photoluminescence and atomic force microscopy. The XPS test shows that the methanol compared to ethanol and isopropanol solvents, the surface of the GaAs after passivation has less oxide content, the As-S bond increases, and the density of octadecanethiol molecules attached to the surface increases. The PL measurement shows that the PL intensity of GaAs surface is highest by octadecanethiol methanol solution passivation, and it is 1.65 times higher than non-passivated. The surface stability test shows that the photoluminescence intensity of passivated GaAs surface do not deteriorate significantly after several days in air (PL intensity decreased by 22.1% within 30 days), which indicates that the self-assembled passivation layer of passivated GaAs surface has good stability.
In order to improve the thermal characteristics of single-chip semiconductor lasers and increase the output power of the device, a new type of vertical packaging structure of heat sink is proposed and analyzed. The heat sink retains the advantages of simplicity and being easy to apply, and the performance of heat dissipation has been improved obviously. The new heat sink structure is believed to be more suitable for packaging of the high-power semiconductor laser chips by heat conduction. Finite-element thermal analysis was used to simulate the thermal field distribution and thermal vector distribution in the conventional structure and the new structure. The simulation results show that the thermal resistance of the conventional structure is 2.0 K/W and the thermal resistance of the new heat sink is less than 1.6 K/W. The theoretical calculation results show that the output power of the packaged laser by new heat sinks can be significantly improved.
A simple approach to generate passively harmonic mode-locked pulse trains in thulium-doped fiber laser based on nonlinear polarization rotation is proposed and demonstrated. Three different ways of mode-locked techniques have been employed in our structure to generate passively high-order harmonic mode-locked pulse trains; 128th-order passively harmonic mode-locked pulse train is achieved in the experiment and the repetition rate is 406.8 MHz. With the increase of the pump power, multiwavelength output can be tuned. A segment of dispersion compensation fiber is used to compensate the dispersion in the cavity; thus, the single pulse width is compressed from 617 to 48 ps.
We designed and manufactured all optical fiber CTD to monitor ocean based on the sensitive characteristics about
optical fiber grating. A series of works have done, including the calibration work for sensor in laboratory, simulated
experiment outside and the local test of ocean parameter. The results we got show that the precision of temperature is
0.01℃ and of pressure is better than 0.1%, both of them overtake the secondary standard of GB/T23246-2009, moreover,
close to the primary standard, and of salinity in laboratory has reached 708 pm/1% closely to the secondary standard. It is
satisfied with the ocean monitoring requirements.
GaAs films have been deposited on substrates of quartz glass by radio frequency magnetron sputtering technique in the atmosphere with or without hydrogen. The GaAs and hydrogen doped GaAs thin films have been studied by X-ray diffraction, scanning electron microscopy. Moreover radial distribution function and pair correlation function
analysis method have been established in order to analyze microstructure further. The as-deposited films are
amorphous at room temperature. The distances between the first neighboring atoms of a-GaAs:H don't change compared
with a-GaAs:H. But Hydrogen restrains reuniting of crystal grain while sputtering and short range regular domains of
a-GaAs:H are smaller than that of a-GaAs. In addition, the morphology of GaAs films is coarser than that of GaAs:H
thin film. The content of hydrogen and the various types of hydrogen bonding have been investigated using Fourier
transform infrared absorption spectroscope.
A novel fabrication method and process of Au(80wt.%)-Sn(20wt.%) eutectic alloys solder with excellent thermal,
electrical and mechanical properties and relatively low melting and reflow temperature was presented, the characteristic
of gold-tin alloy solder and the key technique to realize highly reliable bonding were discussed.
Hydrogenated amorphous silicon (a-Si:H) thin films have been prepared by DC magnetron sputtering, and the effect of
sputtering power, the hydrogen flow rate on deposition rate and the optical properties of a-Si:H thin films have been
investigated. The hydrogen content (CH) of the films was calculated by Fourier transform infrared (FTIR) spectroscopy
method, the maximum CH was obtained at 11at. %,and a bandgap of a-Si:H thin films was changed from 1.43 to 2.25 eV
with different CH. It was found that the refractive index (n) and extinction coefficient (k) of the prepared films decreased
with the increase of CH. The results provided experimental basis for preparing a-Si:H thin films with special performance and structure .
This paper mainly discusses the Si film which is deposited on the GaAs substrate with the IBAD E-beam coating system. By changing the technical conditions to get Si film with different parameters. Further studied on the test, and optimized processing parameter to get final Si film with more dense structure, higher index and minimum absorption. At the same time, considering the better stress matching of the substrate, selected minimal possible layers but realized even more reflection in the process of matching lower index materials. The mainly parameters are temperature of substrate, vacuum pressure, deposition speed and different gas flow, etc. Detailed analysis and evaluation based on the measuring curves and result of the Si test are presented.
High power laser bars become more and more important for pumping of solid-state lasers, medical applications, optical data storage, display, and material processing such as welding, cutting, or surface treatment. Diode lasers array emitting at 980 nm has excited considerable interest as optical pumping source for the Erbium-doped fiber amplifier (EDFA), cladding pumped fiber amplifiers or fiber lasers. A high power multi-mode 980 nm InGaAs laser arrays grown by MBE are reported. Non-absorbing windows are integrated at the ends of the cavity to decrease the light density on the mirror for high power operation. A QCW output power of 64.8 W for lasers array with coated facets is achieved. The threshold current is 7.5 A. The lasing spectrum is peaked at 978 nm with a FWHM of 2.5 nm.
A novel structure for high peak power output of semiconductor lasers has been designed with a weak optical absorption region near cavity facet and a low optical energy density distribution on both front and back cavity facets has been realized simultaneously. The device has been fabricated with a standard MBE grown AlGaAs/GaAs material wafer, and a stack assembly of five laser chips has been finally obtained. The measured stack has a maximum peak power output of 300W with a whole emitting aperture of 2×0.5mm2 and a satisfactory farfield (θ⊥) output property is also achieved with θ⊥ of 31o.
AlGaAs/GaAs material diode lasers grown by MOCVD using TBA as the group-V source and N2 as the carrier gas, was reported. Lasing has been successfully achieved with a low threshold current density of 506 A/cm2.
High power InGaAsN triple-quantum-well strain-compensated lasers grown by metal organic chemical vapor deposition (MOCVD) were fabricated with pulsed anodic oxidation. A maximum light power output of 304 mW was obtained from a 10-μm stripe width uncoated laser diode in continuous wave (CW) mode at room temperature. The characteristic temperature of the lasers was 138 K.
This paper presents the structure design and fabrication technology of 850nm superluminescent Diodes (SLDs).Various ways have been tried for the suppression of F-P lasing oscillation to realize superluminescence: Tilted-stripe structure, tandem-type structure and non-injection section near the rear facet are introduced. Three structures are also compared and combined with each other. The device not lasing at maximum injection current 200mA is realized. At injection current of 150mA, the maximum output power can be 7.8mW and the device can still work at 100°C.
This paper presents the structure design and fabrication technology of 850nm wavelength high power wide spectrum Superluminescent Diodes (SLDs) as non-coherent light source, for the application of fiber gyroscope and other areas. Quantum Well epitaxial structure, unpumped absorbing region structure and facet coating methods have been adopted for enhancing the gain coefficient, output power and the reduction or elimination of lasing oscillation. As typical device performance results, SLDs have been demonstrated with central wavelength of 848-851nm, spectrum FWHM no less than 20nm, and no less than 7mW output under 120mA injection current. The devices operated up to 100°C.
980nm InGaAs/GaAs separate confinement heterostructure (SCH) strained quantum well (QW) laser with non-absorbing facets is fabricated. The microchannel coolers is designed and fabricated with a five-layer thin oxygen-free copper plate structure. We report the operating characteristics of 980 nm high power semiconductor laser stacked arrays packaged by microchannel coolers. A highest CW output power of 200 W for 5-bar arrays is obtained.
980nm InGaAs/GaAs separate confinement heterostructure (SCH) single quantum well (SQW) laser is grown by MBE. Photoluminescence and X-ray double crystal diffraction of the epilayer demonstrate good optical and crystalline quality. A QCW output power of 64.1W is achieved for a cm bar, which is limited by the current source. No thermal rollover in the output power is observed. The threshold current is 18.6A at 15°C. The slope efficiency is 1.14W/A with a corresponding power efficiency of 31.7%.
In this paper, through the analysis and in consideration of the facts which influence on the ultimate output power of semiconductor laser. we report a novel 940nm semiconductor laser array structure with nonabsorbing facets to avoid the COMD on facets. The 940nm laser wafers are grown by MBE. The lasers were cleaved into cm bars. We have made a new design variant of laser array with nonabsorbing facets and coated high-and low-reflectivity coating (approx.95% and 5%). The emission wavelength of the laser arrays is 939nm. Continuous wave (CW) output power of 15 W has been achieved.
In this paper, we report on structure design of high-power InGaAs/AlGaAs/GaAs fold cavity surface-emitting laser (FCSEL) with 45 degree(s) intracavity micro-mirror. The epitaxial material for these devices was grown by molecular beam epitaxy (MBE) technique. Optical and structural characteristic of the film was studied by photoluminescence (PL), X-ray double crystal diffraction and electrochemical C-V profiling method. The radition wave length 0.921um of sample is obtained at low temperature (10K) PL spectrum. The results of X-ray double crystal rocking curve and low temperature (10K) PL experimental show the structure design of folded cavity surface-emitting lasers is realized By MBE.
In this paper ,high quality AlGaAs/GaAs single quantum well(SQM) structure is grown on (100) GaAs substrate by molecular beam epitaxy (MBE) system. Optical and structural characteristic of the film was studied by low temperature (10K) photoluminescence (PL) and X-ray double crystal diffraction method. Using X-ray kinematical theory, we calculated the structure parameters of each samples, the reason for the appearance of the interfering fringes and splitting peaks in double crystal rocking curve were analyse theoretically. The deep levels which affect character of the material and laser are also discussed. The experimental results show that measuring methods of the photoluminescence and X-ray double crystal diffraction are very important for testing the quality of quantum wells and improving the MBE technology.
In this paper we report a 980 nm InGaAs/GaAs MQW semiconductor laser array. The epilayer structures are grown by MBE. We have fabricated broad areas lasers with a cavity length of 1000micron and a stripe width of 6micron and a stripe spacing of 100micron. The measurements are performed in quasi-continuous wave mode (QCW). The highest QCW output power of 12W for laser array with coated facets is achieved. The threshold current density is 400 A/cm2 at 15degree. The slope efficiency is 0.74W/A. The lasing spectrum is peaked at 979.4 nm with a FWHM of 3nm.
In this paper, through the analysis and in consideration of the facts which influence on the ultimate output power of semiconductor laser, we have designed a laser structure with gradient refraction index separate confinement single quantum well (GRIN-SCH-SQW) and have grown the laser structure by MBE. Moreover we have also fabricated array lasers by broad area structure. The lasers are cleaved into cm bars and coated with high- and low-reflectivity films (approx. 95% and 5%). The QCW output power of the array laser has reached 60 W (100 microsecond(s) , 500 Hz), the peak wavelength of the device is 806 approximately 810 nm.
In this letter we report a novel 980 nm semiconductor laser array structure with nonabsorbing facets to avoid the COMD on facets. The 980 nm laser wafers are grown by MBE. Using quantum-well intermixing, we have fabricated nonabsorbing mirrors on the laser array's facets to resist COMD. The quantum intermixing process involves the deposition of a thin film (200 nm) of sputtered SiO2 and a subsequent high temperature anneal (680 - 760 degrees Celsius). The cm bars are cleaved to lengths of 1 mm and their rear and front nonabsorbing facets are coated respectively with high and low reflectivity dielectric film by electron-beam. The devices are bonded p-side up onto copper heatsinks using indium solder and mounted on a water-cooled stage which is held at 18 degrees Celsius for all experiments. The emission wavelength of the laser arrays is 980 nm. Continuous wave (CW) output power of 8 W has been achieved.
In this paper, we adopted GaAlAs/GaAs SCH single quantum well wafer, which is grown by MBE, to complete one centimeter monolithic laser arrays, and two array structures were carried out on purpose to obtain cw and quasi-sw laser output respectively. In the experiment, by means of twice photoetching and chemical etching methods were used to isolate active regions to prevent photons from passing from one to another and amplified spontaneous emission. Results were presented for arrays which reach a maximum cw output power of 7 W perfacet and 50 W (200 microsecond(s) , 50 Hz) quasi-sw output, with lasing wavelength 806 - 810 nm.
In this work, we report Al-free InGaAsP/GaAs separate confinement heterostructure single quantum well structures for lasers emitting at 808 nm are grown by enhanced liquid phase epitaxy. The highest continuous wave output power is 4 W for lasers with coated facts. The differential efficiency is 1.32 W/A. The record characteristic T0 of the laser is estimated to be about 218 K between 10 degree(s)C and 40 degree(s)C from the temperature dependence of the threshold current density Jth.
By using a recently modified LPE technique, extremely uniform InGaAsP/GaAs SCH SQW structure materials could be grown reproducibly. Single stripe lasers with 150 um emitting aperture generate 4.0 W in CW by improvement of waveguiding parameters and ohmic contact process.
KEYWORDS: Semiconductor lasers, Liquid phase epitaxy, Quantum efficiency, High power lasers, Waveguides, Heterojunctions, Temperature metrology, Quantum wells, Diodes, Chemical species
A detailed operating characteristics of InGaAsP/GaAs separate confinement heterostructure single-quantum-well wide-stripe lasers emitting at 808 nm grown by liquid phase epitaxy is reported. The temperature dependences of the lasing wavelength (lambda) , the threshold current density Jth and differential quantum efficiency (eta) d are studied. The effects of the cavity length L on the threshold current density Jth and the differential quantum efficiency (eta) d are studied. The threshold current density Jth increases with increasing temperature T. But the increase of Jth with temperature T is slightly deviated from the exponential dependence. The data fitting of Jth with between 10 degree(s)C and 40 degree(s)C demonstrates a record characteristic temperature T0 of 218 K, indicating a minor influence of temperature on Jth.
It was observed that a twin-lobe like farfield appeared more obviously with larger stripe width of BA LD, also with increasing injected current, due to much more complicated lateral modes. As a consequence, a single-lobed farfield output of 2.0 W has been realized with BA InGaAsP/GaAs SCH SQW lasers (stripe width 150 um).
The LPE growth characteristics of ultra-thin quaternary InGaAsP alloy on GaAs substrate with different sliding speeds and various graphite growth cells has been described. The properties of grown layer are charactered by SEM, photoluminescence spectrum and x-ray diffractometer. Ten to fifty nm InGaAsP layer can be easily obtained and the FWHM of PL spectrum is about 14 mev at 10 K.
This paper presents new results obtained recently in studies of separate confinement structure InGaAsP/lasers. Using Russia's technology, the InGaAsP/GaAs lasers based on QW structure can be produced y a short-time liquid phase epitaxy employing a modified sliding boat technique. The interface abruptness in the InGaAsP/GaAs lasers can be made comparable to the lattice constant. Using 100 GaAs substrates, InGaAsP/GaAs SCH SQW lasers were fabricated and the following values of the main parameters were obtained: lasing wavelength (lambda) equals 808 micrometers , threshold current density Jth equals 100A/cm2, and power conversion efficiency N $eq 56 percent at a CW power of 1W for a laser with a stripe width W equals 100micrometers .
A modified liquid phase epitaxy method was used to grow InGaAsP/GaAs SCH SQW multilayer structures for the diode lasers emitting at 0.81 micrometers . In order to prevent the phosphorus evaporation from source melts, the epitaxy process was carried out at the temperature as low as 750 degrees C. The lowest threshold current density Ith was 300A/cm2, the very high value of the total differential quantum efficiency obtained from long-cavity diodes exceeded 80 percent, the highest CW optical power obtained without any coatings was 2.1W.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.