This PDF file contains the front matter associated with SPIE Proceedings Volume 7420, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

(SiC)_x (AlN)_1-x Solid-solution films were deposited on on-axis Si-face 4H-SiC (0001) substrates by the physical vapor transport (PVT) method. Attempts were made to dope this film with Nd⁺³ for high power laser applications. SiC or its alloys will have better properties compared to oxides because of extremely high thermal conductivity and damage threshold. The doped film was characterized for its quality by X-ray, Photoluminescence (PL) and scanning electron microscope (SEM). X-ray rocking curves showed that crystals with FWHM of less than 200 arc seconds could be grown. The results were compared with previous results published on rare earth doped SiC material. Effect of annealing at high temperature on PL characteristics is also reported.

Dewetted Bridgman is a crystal growth technique in which the crystal is detached from the crucible wall by a small liquid free surface at the level of the solid-liquid interface, called liquid meniscus, which creates a gap between the crystal and the crucible. Dewetting phenomenon was first obtained in space experiments during InSb Bridgman solidification performed on Skylab-NASA mission-1974, and subsequently in many experiments carried out in orbiting spacecrafts (microgravity) on a wide variety of semiconductors. Since the most important aspect of dewetting is the huge improvement of the crystalline quality (reduction in spurious nucleation, fewer dislocations, lower stresses, etc.), this phenomenon has attracted considerable attention and opened the possibility to reproduce experiments on the earth - obtained by applying a gas pressure difference ΔP= P_(cold) - P_(hot) between the cold and hot sides of the sample. The experiments have shown that using uncoated and coated crucibles, detached and partially detached growth can be obtained. Because our interest is to grow crystals with stable gap, the static stability of the menisci in the cases of the classical semiconductors grown in (i) uncoated crucibles (θ_c+α_e<180°), and (ii) coated crucibles (θ_c+α_e≥ 180°) is studied in zero gravity and terrestrial conditions. Numerical results are given and compared with experimental data.

Various space telescope array systems are being considered to investigate other terrestrial planets orbiting around nearby stars in order to find extra-terrestrial life. One of them is the DARWIN mission of the European Space Agency (ESA). The required technology is the nulling interferometer. The challenge of nulling is making the null in the interferometric signal sufficiently deep to cancel the light from the bright star during the collection of light from its surrounding planets. The performance of the nulling is limited by the wavefront quality of the beams. The wavefront error can be reduced by filtering using a single mode fiber. For the DARWIN mission, the operational wavelength range is 6.5-20μm. Within the current ESA project, this is covered by a dual-band fiber system. A chalcogenide glass fiber based on the Te-As-Se (TAS) composition is selected to be used for the short wavelength band. For the long wavelength band up to 20 μm, Tellurium based glass is proposed. Different samples of various composition based on Te glass are manufactured and tested. The fibers are designed by TNO and different prototypes have been manufactured by the University of Rennes. Test setups are developed to demonstrate/investigate the single mode operation. Cladding modes are found to disturb the single mode operation. The effect of cladding modes is modeled. Solutions to eliminate the cladding modes are investigated and tested.

An artificial engineered structure of nano-inclusion made of metallic nano-rods embedded in a dielectric (ε=12.96) matrix with hexagonal arrangement is proposed. New improved designed structure exhibits Negative Refraction (NR) in visible region by using surface plasmon wave in metallo-dielectric photonic crystal operating in a dispersion regime with anti-parallel refracted wave vector and Poynting vector. Finite Difference Time Domain (FDTD) simulations are carried out to study the reflection and transmission properties and obtained Far-field pattern. Designed structure gives NR with high transmission and act as a filter with a quality factor ≈ 10² with strong application potential in nano-optics and nano-technology.

In the proposed paper, we present the guiding properties of chalcogenide Photonic Crystal Fiber (PCF) with square and hexagonal arrangement of air holes in the cladding. The dispersion curves of chalcogenide PCF with different hole-to-hole spacing and air hole diameter have been calculated. Application specific design of dispersion properties like zero dispersion at any wavelength and negative dispersion will be reported for chalcogenide PCF. A comparison between hexagonal and square lattice of chalcogenide PCF has also been performed.

In this paper, we discussed the method for optimization of fiber-optic surface plasmon resonance (SPR) sensor and the effect of optimized parameters by analysis of the transmission spectrum of waveguide-based SPR sensors. Because of their high sensitivity, the SPR sensors can be used in a lot of chemical and biological studies, but it is difficult to perform a theoretical analysis of an SPR fiber sensor. Therefore, for the design and analysis of the sensor responses, a fiber-optic SPR sensor can be optimized numerically by adjusting parameters such as the thickness of metal layers and the grating period, etc. We simulated and optimized parameters by employing the method of the rigorous coupled wave analysis and the genetic algorithm. Also we discussed the methods for improving sensing capability.

We utilize analysis of third harmonic generation under femtosecond pulsed excitation as a reference free measurement method for third order nonlinear susceptibility (χ⁽³⁾ or "Chi 3") of planar waveguides. We investigate χ⁽³⁾ dispersion in planar Ta₂O₅ waveguides at wavelengths either side of the telecoms window, obtaining a nonlinear coefficient of 2 ×10⁻¹³ esu, at 1550 nm. Our study indicates that χ⁽³⁾ increases within the measured wavelength range due to a threephoton resonance of Ta2O5 electrons, revealing the potential of this material system in high speed integrated nonlinear optical switches for the telecommunications spectral window.

A nanosecond pulsed laser deposition at room temperature was used to fabricate a waveguide of Sic:Ge:Fe . The waveguide was used as an optical sensor to detect the sound wave disturbance under water. It was observed that the HeNe laser drives the optical sensor to produce multiple diffraction rings, which are affected by the sound wave disturbance to produce unique clusters of rings with elongated shape pointing away from the source of the acoustic waves. It was observed that, the shape of the rings resonance with the waves to produce either constructive or destructive interference pattern which produce the elongated shape. The Sensor has the same results if it is driven by either HeNe laser or Ar ion laser. The optical characterization of the sensor's performance under harsh environment will be presented as well.

The surface plasmon polaritons (SPPs) have been researched intensively, the very low coupling efficiency of the SPPs brings about difficulty in practical experiment. We proposed a unidirectional coupler for the SPPs using total external reflection. If the high-index dielectric is located on the left side of the slit, the SPPs toward the left side cannot propagate due to the cut-off property, and they should be totally reflected. By properly designing the structure parameter for constructive interference between the reflected Spp mode and the right-ward propagating SPP mode can happen, resulting in enhancement of the coupling efficiency of the SPPs.

Interference transmission filters that have a defect layer incorporated photonic crystal structure provide a narrow transmission notch within a wide stop band. The location and width of transmission notch can be tuned by changing the thickness of the defect layer. In this paper, we propose and implement interference filters with defect layers patterned with diffractive optical elements. The spectral transmission is a function of the local defect layer thickness while the spatial transmission follows contours of equal optical thickness. The novel devices have multiplexed spectral and spatial transmission characteristics. Alternating layers of silicon oxide (SiOx) and silicon nitride (SixNy) were grown onto a clean silicon substrate using plasma enhanced chemical vapor deposition (PECVD). A thick defect layer of SiOx was grown and the wafer was removed from the growth chamber. The wafer was then patterned with charge 2, 8-level vortex structures on a GCA 6300 g-line stepper tool. The devices were interrogated with a collimated beam from a tunable laser source that operates from 1520 nm to 1630 nm. The spectral transmission was measured by separately illuminating each level of diffractive element and the spatial transmission was imaged on to a CCD camera. Spectral transmission peaks whose location varies as a function of level height were obtained. The spatial transmission profiles consist of triangular zones with wavelength dependent orientation. The elements have potential applications in hyper spectral imaging, pupil filtering, and engineered illumination systems.

Two-beam coupling (TBC) in a photorefractive polymer using transmission and reflection geometries is investigated. With drift (due to an applied electric field) and diffusion, a linearized analysis suggests a phase shift between the intensity grating and the induced refractive index grating different from the ideal value of 90 degrees, which is supported by experimental results using a transmission grating geometry. In a self-pumped reflection grating geometry, which is also experimentally studied, the phase shift can be closer to 90 degrees due to a shorter grating period. Absorption and absorption gratings during TBC is also experimentally investigated.

We report a simple yet effective method to improve the accuracy of an optical current sensor (OCS) by compensating the temperature dependency of the Verdet constant with a low-power source operating at a known frequency combined with a lookup table. Neither a complex digital signal processing system nor extra rare earth bulk glass material is used to achieve the accuracy of the current's measurement. Modeling and simulations are carried out. An OCS has been designed and fabricated. The dynamic range of 1620 RMS ampere with a sensitivity of 0.36 ampere is achieved with a single-path SF57 bulk glass.

In this paper, we have reviewed our recent works on IR supercontinuum generation (SCG) and its applications. First, we provide a brief introduction on the motivations of the proposed effort. Second, the work of SCG in single crystal sapphire fibers is reviewed. Third, in addition to single crystal sapphire fibers, the method, the process, and the results of fabricating other IR waveguides are presented. Fourth, a quantitative simulation on the supercontinuum generation with the new IR waveguide is provided, which shows that it is possible to generate SCG beyond 5 microns. To the best knowledge of authors, this is the longest SCG reported so far. Finally, more experimental results of chemical analysis with supercontinuum source are presented.

In this study, we have derived equations for the pyroelectric and photogalvanic contribution to the electrical charging of the photosensitive ferroelectric crystal. Standard photorefractive equations are supplemented by the equation of state for the polarization density following the Devonshire-Ginsburg-Landau (DGL) approach. The photogalvanic voltage and current is considered for a wide intensity range, which includes the CW and the pulsed photo-excitation with high intensities when the impurity is fully ionized and when the traditional linear-recombination approach is not valid. The crystal electrostatic accelerators, based on charging of ferroelectric crystals by pyroelectric and photogalvanic effects, are discussed in relation to the generation of the self-focused electron beam, X-rays, and neutrons.

This paper discusses measurements of non-stationary optical signals using an acousto-optic spectrometer. Any spectral measurements should take non-stationary forms of optical signals into account. The paper presents the results of experiments where a non-stationary optical beam from an electric spark was used. An acousto-optic tunable filter based on off-axis diffraction in the TeO₂ crystal was used. The total analysis time was approximately 1 sec for an optical signal cycle of 100 Hz. The spectrum had a "black body" shape with distinguished fragments at 572 nm and 471 nm. The paper also proposes a method to increase the accuracy of measurement.

Because of the high density and high parallelism of the volume holographic storage, volume holographic correlator can be used as parallel multiple pattern filters. It has a natural feature for the parallel optical computing. However, the applications of this kind of correlator are limited due to low accuracy of the computing results and small number of parallel channels. To improve the data processing accuracy, some methods are proposed and employed to reduce the noise and computing error of the volume holographic correlator. The sidelobes of the correlation pattern can be totally suppressed. The shapes of the correlation patterns are made uniform. And the detected intensity can approach the inner products of the input images and the stored images. The computing speed of the correlator based on the current optoelectronic elements could be nearly two or three magnitude orders over the computing speed of traditional electronic processors. The applications of volume holographic correlator in the star field identification are demonstrated.

Miniaturized Whispering Gallery Mode (WGM) temperature sensor has great potentials of high resolution and great on-chip integration capability. This study focuses on the development of this kind of sensor based on the shifting wavelength of the optical resonance due to thermal expansion and thermo-optic effects of a silica microsphere. Excellent linear dependence of the wavelength shift versus temperature rise is observed for three sizes of microspheres (D=90μm, 145μm and 313μm) in small temperature ranges (≤17K) at very low temperatures (113±1K to 173K). By comparing this observation with the results of similar sizes of microspheres of our previous study in near room temperature as well as with a theoretical analysis, a conclusion is drawn that thermal expansion and thermal optic coefficients need to be further studied for microscale silica materials. Ultra high resolution sensing capability as well as potentials of integrated & miniaturized applications of the WGM temperature sensor is discussed. A method is designed to initially characterize the WGM temperature measurement noise level due to self-heating effect of the WGM resonance.

This paper explains the operation of a quantum Hadamard gate using photonic crystal structures. This is done by simulating a Y-junction beam-splitter in photonic crystal lattice. Normal modes in waveguides are used as qubits. Photonic crystals have been realized by stacking dielectric rods in air in the hexagonal lattice configuration. Index of substrate is chosen as 1.325 and angle of bend is 30°.

Optical responses of a modulation doped lattice-matched InGaAs/InAlAs single quantum well structure grown by gas source molecular beam epitaxy were characterized by photoreflectance PR at various temperatures and depths. Two features corresponding to the ground state transition coming from the SQW and the band gap transition generated from the buffer layer are observed in the PR spectra and agree with those calculated theoretically. The optical transitions were perturbed by the energy shifts of the electronic states due to Stark effect induced by the doped result. The values of the Varshni coefficients of InGaAs/InAlAs were obtained from the relation between the exciton transition energy and the temperature. The built-in electric field could be determined and located from a series of PR spectra by sequential etching processes. The results suggest that a built-in electric field exists at the buffer/substrate interface.

In this paper, the application of a broadband spatially coherent IR supercontinuum source to the biomedical imaging and detection is presented. New IR material is proposed to generate Mid-IR supercontinuum above 4um, which was previously difficult due to inherent material absorption. Broad Mid-IR supercontinuum is numerically shown to be possible with one single wavelength pump in appropriate fiber structure. Mid-IR broadband sources are very useful in IR Optical Coherence Tomography (OCT) and spectroscopy in biomedical materials, due to the rich absorption structures the Mid-IR region. Broadband Mid-IR source is better than single wavelength tunable source, such as Quantum Cascaded Lasers (QCL), for faster analysis speed, since slow scan is not required.

In this paper, some of our recent works on the design of different types of nanostructured surfaces, the terahertz generation, terahertz lenses, and terahertz metamaterials are reviewed and discussed. The mechanism behind the terahertz radiation is the photoelectric emission effect, which leads to the oscillating motions of emitted electrons and are affected by the electric field inside the metal. Furthermore, by using those nanostructured surfaces, terahertz lenses, which are due to the excitation of surface plasmons, and terahertz metamaterials, which results from the effective inductor-capacitor resonator, are also presented.

In this paper, the separation of transmitted and diffused light beams in a scattering medium by a magneto-optical ultrafast switch is investigated. The magneto-optical switch previously developed by the authors is capable of 1 ns switching speed and has a 1 mm clear aperture. The diffused light beams and ballistic beams in a scattering medium are simulated in the lab by two beam paths. One beam is delayed from the other to simulate the diffused light beam and the ballistic beam, respectively. The magneto-optical switch is synchronized with the required delay to the laser pulse to keep only the ballistic beam, acting as an ultrafast light gate. The concept is demonstrated with a 532nm Q-switched pulsed laser.

The instantaneous preferential domain nucleation effect of the z-cut hafnium-doped congruent LiNbO₃ crystal is investigated. The beam from an Ar-ion laser with 514 nm wavelength is focused on z surface. Two incidence schemes are performed: (1) irradiating near and focusing on the +z surface; (2) irradiating near and focusing on the -z surface. The digital holographic interferometry is used in investigating the visible laser-induced domain nucleation in hafnium-doped congruent LiNbO₃ crystal, and reconstructs the phase shift of new domain. From the investigation of phase shift induced by the domain inversion, the analysis of domain nucleation is performed. When the electric field exceeds a certain threshold value, the preferential domain nucleation is achieved instantaneously at the focal spot during the combined actions of irradiation and external fields. The nucleation fields have a systematic decrease with increasing laser intensity, and reach an effective saturation at higher intensities. The reduction proportions obtained in the second scheme are lower than those in the first one with the same intensity, and the saturation values at higher intensities are the same in both schemes. We attribute the instantaneous effect of laser-induced domain nucleation to the space charge field, and the saturation value at higher intensities is related to the saturation of the space charge field. The formation of instantaneous effect and corresponding physical explanation based on space charge field are present.

The phase-mapping of domain wall kinetics under the uniform steady-state electric field is achieved and investigated in the LiNbO₃ crystals by the digital holographic interferometry. We obtained the sequences of reconstructed three-dimensional and two-dimensional wave-field phase distributions during the electric poling in the congruent and near stoichiometric LiNbO₃ crystals. The phase-mapping of domain wall motions in the two crystals are obtained. Both the phase relaxation and the pinning-depinning mechanism are observed during the domain wall motion. The residual phase distribution is observed after the high-speed domain wall motion. The corresponding analyses and discussions are proposed to explain the phenomena.

We have achieved an all-optical tuning in photonic crystal fiber (PCF) by filling the photoresponsive liquid crystal (LC) into the air-hole cladding. The photo-induced phase transformation of the photoresponsive LC modulates the effective refractive index of the photoresponsive LC-filled air-hole cladding, thereby creating an optically tunable environment. Under the laser irradiation the output intensity of guided light can be modulated by the photoresponsive LC-filled photonic bandgap structure. The tuning behavior of the guided light is independent on the polarization direction by using the linear-polarized He-Ne laser as probe. We also demonstrate the potential use of photoresponsive LC-filled PCF in all-optical communication device using an optical spectrum of wide bandwidth amplified from an erbium-doped fiber amplifier (EDFA) system.

Holographic scattering noise in LiNbO₃:Fe:Ru crystals is investigated in this paper. The effect of doped concentration and the incident light intensity on the holographic scattering noise is investigated. The experimental results show that the transmitted light intensity is fluctuated in the initial stage of scattering noise evolution, and the sample with highly doped concentration has the lowest scattering noise level among three LiNbO₃:Fe:Ru samples. The results are analyzed on the basis of multi-wave coupling amplification mechanism and the saturated space charge field.

An opportunity of realization of optical memory and optical switching under the two-wave action on 1D photonic crystal (layered structure) with cubic nonlinearity is demonstrated on the base of computer simulation. Proposed scheme of interaction concludes in an action of laser pulse with different wavelengths. First, after action of one of them an optical soliton appears in some layers and part of optical energy localizes in nonlinear photonic crystal. Then, a pulse with different wavelength acts on the photonic crystal. As a consequence of it, the light energy of laser pulse with the previous wavelength leaves the photonic crystal while the laser energy of acting pulse localizes in the crystal due to formation of new soliton in this layer. This process can be repeated many times. The replacement of radiation with one wavelength on radiation with other wavelength takes place under the action of sequence of laser pulse with definite wavelength. A duration and maximum intensity of pulse from this sequence determine a speed of light energy exchange and an efficiency of radiation replacement.

Thermal management has the important influence in quantum effect of light emitting diodes (LED) based on printed circuit board (PCB). In the industrial processing, the quality of the thermal dissipation is decided by the gumming technique between the PCB and aluminum plate. Because it transfers the heat from electric device to the aluminum plate, which completely removes the heat. In this study, a superior method, alumina thin films, soldered the LED lamps to enhance the heat transfer. The films were fabricated onto 1070 aluminum alloy substrate by plasma spraying, vacuum sputtering and electric plating technologies. The dielectric coatings were characterized by several subsequent analyses, especially the measurement of thermal resistance. The X-Ray diffraction (XRD) diagram analysis reveals that alumina phases were successfully grown on the individual substrate. Compared to alumina coating fabricated by plasma spraying and electric plating technologies, vacuum sputtering creates low sheet resistivity, high hardness, high critical load, and good thermal conduction of 119 W/m-K.

In this paper, we propose silicon-on-insulator (SOI) based Photonic Crystal waveguide with hexagonal arrangement of elliptical air holes embedded in silicon material for slow light transmission. Delay bandwidth product which indicates the buffering capacity is evaluated to be record high 87.41 and large bandwidth (≈ 4.4THz) below silica light line. Within this bandwidth, group velocity dispersion is evaluated on the order of 10⁰-10² ps²/km. Thus in the proposed structure, light is confined horizontally by photonic band gap, vertically by total internal reflection and longitudinally by low dispersion and low group velocity while propagating through the waveguide.

The development of theoretical and experimental method for the characterization of Polarization Maintaining Photonic Crystal Fiber (PM PCF) from far filed intensity measurements has been reported. To maintain the polarization in PCF different air hole diameter along orthogonal axes adjacent to the core region has been introduced. This helps in creating an effective index difference between the two orthogonal polarization modes. It is shown that air hole spacing (Λ), air hole diameter (d) and effective cladding index differences of PM-PCF can also be obtained from its far field measurements.

Effect of magnetic nanoparticles on the transparency of a transparent matrix is studied in the infrared wavelength region. We used the iron oxide - potassium bromide system for this study. Several samples were prepared with different concentrations of iron oxide nanoparticles. IR microscopy and transmission measurements were performed to determine the resonance characteristics of aggregates of nanoparticles. We observed a sharp strong absorption peak at 7.22 μm. The amplitude of the absorption peak was dependent on the nanoparticle concentration. Effect of interface diffusion on the morphology and transmission was studied by annealing the sample at 175 C and 500C. High temperature annealing indicated interpenetration and affected the transparency significantly.

Experimental studies of laser light intensity profiles, with light propagation direction perpendicular to the optical c-axis, in ferroelectric single crystal fibers such as LiNbO₃ are carried out and reported. Theoretical simulations of such multimode propagation of light are also conducted for the LiNbO₃ single crystal fibers. The simulation and experimental studies are extended to and compared with the commercially available single mode and multimode silica optical fibers. Theoretical simulations provided a good account for the light intensity profiles measured and led to a preliminary interpretation of complex specklegram observed in anisotropic single crystal fibers.

Recently, we proposed a new speckle-based hologram multiplexing recording technique. In this method, a multi-mode LiNbO₃ single crystal fiber is employed to generate speckle patterns which are used as reference beams in hologram recording process. The compact modulation architecture of this new technique allows a fiber array structure which can dramatically increase the system storage capacity as well as realize image adding function. To explore the functionality and the performance of a fiber array structure, a dual-fiber configuration has been set up in our laboratory and the preliminary experimental results are presented in this report.

Considering the singly pump-resonance in a lossy lithium niobate waveguide with quasi-phase-matched apodized stepchirped domains as a broadband frequency doubler, the optimized values of back-facet reflectivity and input power have been calculated to obtain the maximum efficiency envelope of resonant modes while the bandwidth remains almost the same as the non-resonant waveguide.

An optimized encoding algorithm is required to produce high-quality computer generated holograms (CGH). For such purpose, we have proposed that usage of the direct search algorithm (DSA) is effective for encoding the Lohmann-type binary amplitude and phase CGH. However, it takes much time for a computation time to get an optical solution by a DSA. To solve this problem, we have newly found that simultaneously selective direct search algorithm (SDSA) is greatly effective to shorten a computing time for encoding a Lohmann-type CGH.

The synchronous paragenesis of piezoelectric resonance together with EO modulation, its effect on the electro-optic probing in low frequency range, and a new voltage calibration technique which can utilize the piezoelectric resonance to enhance the voltage sensitivity of EO probing, are reported for the first time.