For spatio-temporal processing of ultrashort-pulse laser beams, design constraints arise from dispersion and diffraction. In sub-10-fs region, temporal and spatial coordinates of propagating wavepackets get non-separable. To enable controlled shaping and detection with spatial resolution, specific advantages of thin-film microoptical arrays are exploited. Transmitting and reflecting components of extremely small conical angles were used to generate multiple nondiffracting beams and self imaging patterns. With novel-type metal-dielectric microaxicons, low-dispersion reflective devices were realized. Beam propagation was simulated with Rayleigh-Sommerfeld diffraction theory. For time-space conversion, matrix processors consisting of thin-film microaxicons were tested. Transversally resolving linear and nonlinear autocorrelation techniques were applied to characterize the space-time-structure of localized few-cycle wavepackets shaped from Ti:sapphire laser beams at pulse durations down to 8 fs. Bessel-like X-waves were shaped and their propagation was studied. In combination with autocorrelation, wavefront analysis of ultrashort-pulse lasers with Bessel-Shack-Hartmann sensors operated in reflection setup was demonstrated.

Self-imaging is demonstrated based on Montgomery’s theory for periodic wave fields and the use of diffractive optical elements. We review the theory of self-imaging, describe the grating design and present experimental results. The presented work aims at building an interferometer that may serve as a tapped-delay-line filter for the shaping of ultra-short light pulses.

The problem of EM wave propagation in non-reciprocal chiral media has been studied by several investigators. In a recent approach, a dual-transform technique has been developed to study the problem of such propagation under paraxial and slow-envelope variation conditions. In this paper, we first outline some of the results obtained using the dual transform technique for arbitrary boundary conditions within the left boundary of a semi-infinite, non-reciprocal chiral medium for a uniform plane wave, and a fundamental Gaussian-profiled beam. Next, we explore the problem of a uniform EM wave incident at an oblique angle at an interface between a reciprocal, non-chiral medium and a non-reciprocal, chiral medium. To carry out the calculations, the appropriate Maxwell's equations are examined together with the necessary boundary conditions, and reflection and transmission coefficients are derived for both parallel and perpendicular polarizations. The results are first tested for convergence in the reciprocal, non-chiral limit, and also for their physical implications under varying interfacial conditions.

Pole-zero diagrams are often employed in electronic filter design because of their simple and direct visualization of spectral characteristics. This paper proposes the use of pole-zero diagrams for tailoring the spectral response of ring resonator array filters for photonic applications. We show that there exist close relations between the pole-zero diagram features of the resonator array and its wavelength response characteristics, and demonstrate that the pole-zero diagram approach could be a very useful tool in the design of photonic devices based on resonator filters. In particular, we employ the pole-zero diagram approach for the case of a parallel-coupled ring resonator array for interleaving, and use this method to produce a new low crosstalk design.

A novel, non-invasive measurement technique for quantitative cellular analysis is presented that utilizes the forces generated by an optical beam to evaluate the physical properties of live cells in suspension. Analysis is performed by rapidly scanning a focused, near-infrared laser line with a high cross-sectional intensity gradient across a field of cells and monitoring their interaction with the beam. The response of each cell to the laser depends on its size, structure, morphology, composition, and surface membrane properties; therefore, using this technique, cell populations of different type, treatment, or biological state can be compared. To demonstrate the utility of this cell analysis platform we have evaluated the early stages of apoptosis induced in the U937 cancer cell line by the drug camptothecin and compared the results to established references assays. Measurements on our platform show detection of cellular changes earlier than either of the fluorescence-based annexin V or caspase assays. Because no labeling or additional cell processing is required and because accurate assays can be performed with a small number of cells, this measurement technique may find suitable applications in cell research, medical diagnostics, and drug discovery.

We present in this paper a data fitting method that analyzes a spherical shell that uses the near orthogonality of the Spherical Harmonics Y_lm(Θ,Φ) within a discrete data collected on a spherical shell to obtain the best rms fit. This is obtained through the generation of an orthogonal basis from the spherical harmonics Y_lm(Θ,Φ) on a discrete and often irregular data set on a spherical shell.

In this paper, a novel all-fiber Acousto-optical tunable filter (AOTF) is proposed, which employs a mode feedback mechanism. It is shown that the proposed AOTF has superior performance with high isolation and narrow linewidth. Simulation studies are done to verify the effectiveness of the proposed filter.

Nanoscale science is playing an increasingly important role in developing future technologies for information systems including computing, telecommunications, display, high-resolution imaging and sensing. Optical and photonic technologies are recognized as enablers in most of these applications. However, construction of artificially engineered nanostructured optical and optoelectronic materials, resonant nanostructures such as photonic crystals, and integrated nanophotonic active and passive devices is one of the most challenging tasks. In order to improve device performance, good characterization tools for structural and functional testing of nanophotonic devices are required. One technique that may be promising for improving visualization, imaging, and characterization tools is based on coherent Near-field Scanning Optical Microscopy (NSOM). This instrument enables quantitative detection of the complex amplitude of the optical near-field of various nanophotonic devices on nanoscale. Amplitude, phase and topography are measured simultaneously by combining an NSOM and a heterodyne interferometer. Its continuous wave (CW) design has been extended with ultra-short femtosecond laser pulses at 1550 μm to investigate phenomena in the optical near field with femtosecond time resolution. The evanescent light of a short pulse has been observed in a waveguide, allowing the investigation of both its spatial and temporal device characteristics.

We review recent progress made towards two types of holographic data storage systems. The first offers the potential for simultaneous search of an entire database by performing multiple optical correlations between stored data pages and a search argument. This content-addressable retrieval produces one analog correlation score for each stored volume hologram. We review work we have performed on fuzzy encoding techniques, experimental demonstrations of hardware-level database searching, on the measurement of true inner-products, on architectures in which massively-parallel searches could be implemented, and on quantifying the inherent speed-fidelity tradeoffs. The second system offers read-write, fast-access data storage. We review systems architectures for extending this high density to high capacity using phase-conjugate readout and signal processing to relieve alignment and distortion constraints.

A complete target tracking processor including a segmentation method based on active contours or "snakes" has been optically implemented and its behavior has been evaluated. The purpose of this segmentation method is to darken the background in order to avoid its disruptive influence on tracking. The optical processor includes a Joint Transform correlator (JTC) with improved performance since with the proposed method the target will appear with a maximum of details in the reference. The complete processor is very complex and depends on the technology of several photonic devices. It consists of three nematic liquid crystal spatial light modulators, a preprocessor using an optical high pass filter, two different channels separated by the polarization direction of the light, a holographic edge enhancement filter, an electromechanical iris diaphragm, a camera and several photodetectors. The complete optical tracking processor must exhibit a negligible response time compared to a tracking cycle. To meet this requirement, research was conducted into two directions -- the algorithms and the components. A new snake optimization criterion is introduced and two different tracking algorithms are compared. The parameters of each component are studied and optimized, and their influences on the performance of the optical processor in terms of speed and tracking accuracy are analyzed. A complete system level demonstration of target tracking is presented as a conclusion.

We study the realization of simple resonant structures allowing to obtain holographic reflection filters under a 45° incidence for a wavelength of λ = 632.8 nm. In particular, we will be interested in the influence of the parameters of the structures on the position and the shape of the resonance peaks. The 45° incidence takes its origin in the will to include resonant components in substrate mode systems. In the second part of this paper, we use the obtained results to study the realization of an active substrate mode spectral filter by the use of an eletro-optic material: zinc oxide (ZnO). The presented results which obtained by an algorithm based on the Rigorous Coupled Wave Theory.

We provide an analysis of a data beam fitting method of N data points on a circular pupil that corresponds to its best rms fit that uses an orthogonal vectorial basis of the N data points. The solutions of many physical problems often result on finding specific solutions of basic functions F_nl(ρ,θ) with polar symmetries that also can be easily treated numerically. Unfortunately, in some other cases, the analytical solution loss its orthogonality by the experimental data discretization, therefore become inadequate for a best rms fit data. On the other hand, by introducing the Schmidt orthogonalization, we can get the best rms fit for the solution in the coefficients of the expansion and in F_nl(ρ,θ). In these cases, where the F_nl(ρ,θ) has a cumbersome convergence, we develop the rms fit based on Zernike like Polynomials and establish the proper transformation. We illustrate in more detail the method by developing a beam analyzer as an application.

A new hybrid optoelectronic technology has been developed which utilizes a very thin layer of light emitting polymer material on a CMOS silicon active-matrix substrate to create a 2-D array of independently programmable optical emitters. The technology has been developed thus far primarily for its use as a microdisplay. Here we detail aspects of device design and characterization. We consider the relevance of the new technology to optical and photonic systems other than displays.

The miniaturization of optical devices is a key objective in the field of photonics, and a large set of materials and techniques are under investigation. Among the former, lithium fluoride (LiF) is of particular interest because it is almost not hygroscopic and it can host stable color centers (CCs) produced by ionizing radiation and emitting in the visible spectral range even at room temperature (RT) under optical excitation. The increasing demand for low-dimensionality photonic devices imposes the utilization of advanced lithographic techniques for producing luminescent structures with submicrometric spatial resolution. We present an innovative irradiation method producing CCs in LiF crystals and films by using an EUV and soft X-ray laser-plasma source. This technique is able to produce colored patterns with high spatial resolution on large (more than 10 cm²) areas in a short exposure time compared with other irradiation methods. The colored LiF samples have been characterized by optical absorption and photoluminescence measurements for different irradiation fluences.

In this work we review the application of twisted nematic liquid crystal displays (TN-LCD's) for image processing, pattern recognition and diffractive optical elements. For these applications, three kinds of spatial modulations are of interest: phase-only, amplitude-only and combined full amplitude and phase modulation. However TN-LCD's generally provide coupled phase and amplitude modulation. We review how to achieve these three desired operating conditions. We begin with a discussion of different Jones matrix models for TN-LCD displays. We examine optical configurations for achieving amplitude-only modulation and polarization eigenvectors for achieving phase-only modulation. Then we review an extremely successful technique for obtaining combined full amplitude and phase modulation by spatially modulating the maximum phase depth.

Ferroelectric Liquid Crystal (FLC) Spatial Light Modulators (SLMs) are attractive because of their high switching speed. However, conventional FLC SLMs are only capable of binary phase modulation. This is inconvenient for beam steering since as much as 60% of the incident power is lost to unwanted diffraction orders. To overcome this problem two cascaded FLC SLMs were used in this work. By coherently imaging a 180° binary-phase FLC SLM onto a 90° FLC SLM, with high precision, an effective four-level phase modulator was realized experimentally. Beam steering was demonstrated in the angular range ±10.9 mrad. The angular inaccuracy of the steered beam was found to be about 0.1 mrad, which equals about 25% of the beam diameter. The beam steering device has also been used for tracking experiments.

This paper presents the development of an electrical SPICE model of a Ferroelectric Liquid Crystal (FLC) on silicon microdisplay. Previous work has investigated the use of an electro-optical SPICE model to simulate the optical response of an FLC cell to a given electrical signal. However, the design of the backplane drive scheme for the display also requires an accurate model of the electrical load represented by an FLC cell. The model presented here provides a good fit to electrical measurement results and, in addition, can be combined with elements of the electro-optical model to allow the optical response of the cell to be modelled at the same time. This paper also presents results of charge collection current measurements which highlight the differences in the behavior of the cell when it is switched between positive and negative voltages and then in the other direction.

In this work we analyze the behavior of complex information in Fresnel domain taking into account the limited capability to display complex transmittance values of current liquid crystal devices, when used as holographic displays. In order to do this analysis we compute the reconstruction of Fresnel holograms at several distances using the different parts of the complex distribution (real and imaginary parts, amplitude and phase) as well as using the full complex information adjusted with a method that combines two configurations of the devices in an adding architecture. The RMS error between the amplitude of these reconstructions and the original amplitude is used to evaluate the quality of the information displayed. The results of the error analysis show different behavior for the reconstructions using the different parts of the complex distribution and using the combined method of two devices. Better reconstructions are obtained when using two devices whose configurations densely cover the complex plane when they are added. Simulated and experimental results are also presented.

We modify the double-phase holographic code to implement arbitrary complex modulation with a transmission type twisted-nematic liquid crystal display. This device is employed in the mostly phase configuration, for which the phase modulation is coupled with a non-constant amplitude modulation. The modified double-phase code implements arbitrary complex modulation employing the constrained complex modulation of the display.

The optical part of a high-speed, inter-chip optical interconnection scheme was tested. In the scheme, electronic data processing units are interconnected by laser beams via a transparent substrate. All the electronic and optoelectronic chips are mounted on one side of the transparent substrate, reflective diffractive optical elements for shaping and deflecting the laser beams located on the other side. To both allow close packing of VCSELs and low reflection losses, physically the transparent substrate is made-up of a thinner quartz plate positioned on top of and in direct contact with a thicker one. The insertion loss on imaging a VCSEL-simulating point source located on the upper side of the substrate onto an 8 mm laterally displaced position on the same side of the substrate via transmission through the substrate was found to be ~10 dB.

Modal noise is an undesired modulation of the guided light intensity in a multimode waveguide. Applying the frequency correlation function the frequency dependence of this noise as well as the bandwidth of a multimode waveguide can be estimated. In this paper the existing model of the frequency correlation function for a waveguide with smoothed dielectric interfaces is enhanced to analyze the influence of surface roughness on the achievable bandwidth. This surface roughness is caused by the manufacturing process of the waveguides.

A compact, low loss, optical tap technology is critical for the incorporation of optical interconnects into mainstream semiconductor processes. Previously, we introduced a vertical multimode interference effect based tap device that had the potential for very high speed optical to electrical performance in compact, rectangular device geometries, and in CMOS compatible processes. In this work, we report on the fabrication and test of various ridge guide based optical tap structures on silicon substrates. The experimental results compared well with simulations. Optimized guide to substrate optical coupling was varied from 2 dB to 3 dB by insertion of a spacer layer. Substrate-isolated (passive) tap structure loss of less than 0.6 dB at 840nm wavelength was measured. Based on the device geometry, this result indicated actual tap excess losses (energy fraction not collected by the substrate) to be less than 0.3 dB. Overall, the test results confirm the low excess loss, multimode interference operation of the new tap design, and pave the way for integration of the tap structures with CMOS photo detector devices.

A highly sensitive pressure sensor based on two Mach-Zender interferometers is described. The interferometer measuring and reference channels are made of single-mode W-lightguides. The measured sensitivity was shown experimentally to be 65•10^-2dB•Pa^-1•m^-1.

An attempt is made to use the phenomenon of colinear acousto-optical interaction in birefringent single crystals for purposes of a coherent optical processing of UHF radio-wave electronic pulses in anti-radar system. The exact and closed analytical model for describing this phenomenon in uniaxial crystalline materials is developed if both the acoustic attenuation and spreading the acoustic beam are allowed for. The peculiarities of collinear acousto-optical interaction in a cells made of lithium niobate single crystal are considered for traveling continuous-wave regime as well as for an acoustic cavity under action of relatively short acoustic pulse. The feasibility of applying such an effect to perform processing radio-wave electronic pulses is analyzed in the paper presented and the corresponding opto-electronic algorithm is elaborated. The results of preliminary experiment with the key component for similar active anti-radar system are presented.

This paper presents a new three-wavelength ring laser using one erbium-doped fiber amplifier. The simultaneous output of three lasing wavelengths is achieved by controlling the gains of different filters through utilizing a cascaded fiber Mach-Zender interferometer (MZI) with the triangular-shaped interference transmission spectrum. The key advantage of the proposed system over existing technologies is that the output is channel-wavelength selectable. Each channel can be tuned individually from one channel wavelength to the other. The channel wavelengths are selectable over the range of 1522-1665nm.

We describe a novel approach to manufacture photonic crystal-based integrated systems based on a two-step process of interferometric patterning followed by optical direct-write of the functional elements. First, the photonic crystal lattice is patterned in photoresist using interferometric lithography, producing a large-area lithographic pattern quickly and easily. Second, the defects in the lattice to implement the functional devices are created using optical direct write with a strongly focused optical beam. After patterning processes, the mask is developed and a dry-etching process is used to transfer the pattern into the substrate. This hybrid approach possesses an advantage in terms of fabrication time and cost as compared to E-beam lithography for the patterning of large-scale photonic crystal-based systems.

A terahertz-scale two-dimensional photonic-crystal waveguide based on a silicon-on-insulator was fabricated, and the optical transmission spectrum was measured. Terahertz beam propagation characteristics were observed using a thermal imaging camera, with incident light in the 10.1-10.7μm range. The measured transmission spectrum was in very good agreement with a three-dimensional finite-difference time-domain calculation.