A new method for microlens profile design was developed based on the analysis to the main parameters of microlens array, including micro profile formation, the numerical aperture ( NA ), the maximum sag depth for the refractive lens and the minimum zones width for the diffractive lens. With the relationships among the parameters, the microlens array in different profile can be determined effectively. The moving mask method[1] is used to realize the required profiles, an unique photolithography system have been built for implementing the mask moving exposure in both X and Y directions for the creation of microlens array. By modifying the binary moving mask, optimizing the photosensitive materials and the processing technique, the microlens profile error can be controlled in the range of 0.4µm~3µm depending on effective reliefdepth of the microlens. In our method, both diffractive and refractive microlens array with larger NA and higher fill factor can be fabricated for satisfying a plenty of purposes.

Photonic polymers exhibit many unique properties that are particularly useful for producing the next generation of optoelectronic integrated circuits. These micro-structured materials that can be effectively formed by using holographic technology contain a periodically modulated dielectric constant on a length scale comparable to the wavelength of light. In this paper, we will present some of our research progress in forming unique photonic polymers using holographic technology and its novel applications in optical true-time-delay circuits, optical clock signal distribution circuits, and micro-scale wavelength division de-multiplexers.

A new method is presented to encode and decode images with computer-generated hologram of fractional Fourier transform. The fractional Fourier transform computer-generated holograms (FRT-CGH) of several objects with different orders are respectively recorded on one holographic plate. In order to reconstruct images of the objects, several fractional Fourier transform systems of certain orders are needed. This method is agile and convenient on design and fabrication. It can be encoded and decoded either by numerical method or by optical method. Because of its particularity of image reconstruction, FRT-CGH is regarded as a new optical security system and may be widely used in the future.

In the spectral dispersive device of this paper more than one volume hologram are superimposed into the common volume of photorefractive material Fe:LiNbO3, permitting acquisition of high diffraction efficiency, high spectral resolution, full spectral coverage, and simple structure. With the Bragg compensatory multiplexing recording technique, this device could be recorded with only one single wavelength laser. The dependence of diffraction efficiency on both material and exposure parameters is investigated in Fe:LiNbO3. A linear discrete-type device working at sixteen discrete wavelengths is designed fabricated. The high resolution and imaging properties ofthis device are also demonstrated in experiment.

In this paper we propose a space multiplexed diffractive optical device based on Talbot effect. Several different diffractive optical elements (DOEs) with the same size and physical aspect, such as Dammann grating, computergenerated hologram (CGH), are arranged interleavely and periodically in the DOE plane to form a multifacet DOE. Then it is illuminated by the corresponding Talbot illuminator. Each of the DOEs in the multifacet DOE can be triggered respectively by the irradiance of the Talbot illuminator. In our experimental setup, two CGHs with the period size of 0.5x0.5mm and pixel size of 5x5µm are incorporated into one multiplexed hologram according to the specific encoding periodic pattern that can be realized with a Talbot array illuminator. The corresponding reconstructed images have been obtained selectively when the relative position of the Talbot illuminator and the multifacet DOE is properly changed, which confirm the feasibility of our method. This device can be used in optical information and optical interconnection.

From two aspects analyze the advantage ofweak optical fiber Bragg grating used as filter to filter the ASE noise of optical amplifier before the signal is detected. Firstly, we calculated the temporal response of the weak optical Bragg grating filter, the matched Bragg grating filter and the commonly used F-P filter. We find that the reflected pulse of weak optical Bragg grating closely resembles the triangular shape characteristic of a perfectly matched filter. It almost has no intersymbol interference. Whereas the pulse from a F-P transmission filter has a long decaying tail. This will lead to errors in detection. Secondly, we simulate the transmission process in computer. Calculating the power SNR(signal-to-noise ratio) of output signal with the same input signal filtered by the optical fiber Bragg grating, matched filter, F-P filter. Analyzing the improvement ofthe SNR after filtered by them. We find it also has advantage over F-P filter. Taking the two reasons into account, the weak optical fiber Bragg grating is superior to the widely used F-P filter. The weak optical fiber grating can be approximate used as a matched filter.

We present a theoretical model in which the two-center band-transport equations and the coupled-wave equations are considered simultaneously to study the dynamic holographic storage in photochromic LiNbO3:Fe:Mn crystals. The optimal conditions for processing and material prescriptions are discussed in detail, which include the steady-state recorded space-charge field and the fixed space-charge field, the dopant concentrations of Fe and Mn, the oxidation/reduction degree, the recording sensitivity, the intensities of the coherent writing beams and the UVsensitizing light. The supporting experimental results are outlined, too. Both theoretical and experimental results verify that effectively oxidized processing, high concentration of Fe dopant, moderate concentration of Mn dopant and optimal intensity ratio ofcoherent writing beams to UV-sensitizing light are necessary for nonvolatile holographic storage.

High resolution and wide-angle Helmet-Mounted Display is the key technology of Virtual reality helmet. Inspired by optical laser technology, and based on the technology of laser television display, the authors suggest a new type of Helmet-Mounted Display Virtual Retinal Display (VRD)

We increase the mass and thickness of CsI film on the base of CsI/MCP (micochannel plate) reflection mode photocathode properly. A part of CsI material is evaporated into 1-1 .5 diameter depth of the channel; another part is coated onto the input surface of MCP. Thus the transmission-reflection combined new type photocathode is formed. When x-rays irradiate the cathode, they penetrate into the coated layer and cause the photoelectron emission, then the rays get into the layer on the walls of MCP, continue to interact with CsI, and produce photoelectrons again. We calculate the quantum efficiency ofthe new type on theory. We also compare the transmission-reflection mode cathode with the reflection mode cathode through experiments of the output current character. The results of the experiment indicate that, the output current of the new type is increased two times than that of CsI/MCP reflection mode photocathode under the same condition and so the quantum effective is increased.

The Optical Computerized Tomography (OCT) is an important means for the research of flow field. In this paper, the Algebra Reconstruction Technology (ART) of OCT is discussed. An improvement for the reconstruction equations has been presented. A property matrix including the prior knowledge is introduced in the reconstruction, and an unfixed ultra relaxation coefficient is adopted, that is to say, giving the coefficient a dynamic range. By this way, the reconstruction precision will be greatly increased, thus the reconstructed field will approach the actual field.

In our paper, OCT is used to measure the distribution of temperature field generated by disc, hemisphere etc. systematically for the first time. The method of this technology is discussed firstly. Secondly the gathered interferograms through Fabry-Pérot (F-P) rotary interferometer are provided and the 3-D temperature distributions of all the fields are given. Then the results are compared with the actual measured value, and the difference is given, which shows the precision can reach 5%. Furthermore, the temperature distributions of several complex objects combined by simple objects are also measured, and the results indicate that the temperature field of complex objects can be combined by that of simple objects through certain way. Because all the complex objects can be regarded as the combination of the simple objects, our researches establish the theoretical and experimental foundations for the research on the temperature field of complex objects.

The nonlinear refractive index model is used to analyze the diffraction properties of reflection volume hologram. Using characteristic matrix method of multi-layer system, we analyzed the wavelength selectivity and angular selectivity of the diffraction efficiency of reflection volume hologram for P and S polarization. Compared to the classic pure sinusoidal index modulation, this nonlinear model gave more practical results.

Optical filter is quite an important measure in optical information processing. In this paper, FIR (finite impulse response) filter theory is employed in optical filter design to set up a novel optical FIR filter model, based on the crystal birefringence effect. Using this model, arbitrary spectrum output can easily be obtained, including double channels. Here we present several optical FIR filter optimization approaches to get good performance and then give both spectrum and angle properties for this fiRer. Furthermore, we also present the experimental implementation and show G/M filter as an example, which has good application prospect in projection display field.

In order to decrease the phase shift error, this paper presented a new object phase shifting method by using fringe stabilizing device to stabilize the interference fringe. The experimental result shows the fringe drift is less than ?/20 in five minutes , and the phase shifting precision is more than 0.004 ? , furthermore the system is very simple, performance reliable and operating convenience, it will take an important role for improving the measure precision of 3-D phase profilometry, more strong practicality and popularly application prospect.

on the theoretic analysis, this paper reports a new two-step color reflection holography and has made some holograms successfully. Comparing with making Denisyuk hologram, this new two-step recording method can adjust the ratio of reference light and object light, and the reconstructing image can be in any location in holographic recording plate.

This paper presents a novel synthetic generated hologram (SGH) system, in which a digital micromirror device (DMD) is used as space light modulator (SLM). In the system, the object light beam is directed through a sequence of digital images on a space light modulator, digital micromirror device (DMD), rather than the transparent films used in the conventional SGH. A computer controlled distributing device replace manual operation. With this system, threedimensional full color hologram can be generated by synthesizing a series of two-dimension digital images, obtained by digital camera or generated by computer software. The preliminary experimental results have been obtained with this system. The possible future development has also been discussed.

Vector coupled wave equations for reflection volume holograms recorded in non-uniform medium are deduced from Maxwell's equations. The diffraction efficiencies of s-polarization and p-polarization propagated in reflection volume holograms recorded in dichromated gelatin (DCG) are measured in detail. On the basis of the experimental data, the non-uniform models of the modulation of refractive index and variation of spatial frequency are established. A fair agreement between the theoretical previsions and the experimental results is achieved. It is shown that the vector coupled wave theory for reflection volume holograms in non-uniform medium is reliable in practice.

Gene-chip as a very useful means of biotechnology has been applied to many research areas such as gene discovery, disease diagnosis and pharmacogenomics etc. , but commercially available gene-chip detection instruments are too expensive to be accepted by common labs. In this paper, a laser confocal scanning system with holographic notch filters used for simple gene-chip detection is presented. The system is mainly composed of an ordinary optical microscope, two holographic notch filters, a He-Ne laser, a digital controlled X-Y platform, a photodetector and a PC. The volume holographic notch filters were fabricated in our lab to substitute for the expensive narrow-band interference excitation filter and the dichroic filter in the conventional confocal detection system. The detection experiment was carried out on the gene-chips hybridized with cy5-labeled targets and the system sensitivity was determined by static measurement. The sensitivity is about 2x10-22mol/µm2, and the resolution is 10µm. The results indicate that the system can be used in primary gene-chip detection.

Silver halide emulsions with average grain size around 10 nm and red-green-blue sensitivities were prepared in our laboratory. The influences of some preparing conditions on the emulsion grain size and spectral sensitivity were discussed. The emulsions were used to record holographic reflection gratings for investigating their properties in reflection holography. The reflection gratings were processed in a modified AAC developer and modified R-10 bleach. Diffraction efficiencies of the reflection gratings were up to 55% for the exposure of I .8 mJ/cm2 at 633 nm, 55% for the exposure of 2.2 mJ/cm2 at 515 nm and 50%for the exposure of3.3 mJ/cm2 at 458 nm.

In this paper a new method has been developed for fabricating micro-optical element by exposing silver-halide sensitized gelatin (SHSG) through real-time mask and etching SHSG with enzyme solution. The principle of etching SHSG with enzyme solution is given in detail and the optimum technique parameters of this process are presented, furthermore the theoretical analysis and solving scheme for the nonlinearities which come from the absorption of light energy by film are given. It is experimentally obtained a good linear relationship in a range of 4µm deep. At last, the micro-cylindrical lens and micro axicon array are achieved by experiment, and the results are evaluated for experiments by stylus profiling instrument and interference microscope.

Fourier transfer is used to analyze the limit of resolution for holographic lenses( HL). Detailed studies on the diffraction field distribution on the focal plane open out the cause that the resolution does not follow the rule of inverse ratio with the radius of aperture. The transimmisivity of HL changing with the radius makes its diffraction field experienced apodization effect, pedestal widen, new side lobe grown out processes, so the figure of the diffraction field distribution changes significantly. For this reason, the location of the first minimum as resolution criterion is not suitable.

A novel technique is proposed to fabricate coded holograms based on dot-matrix holograms for security applicaitons. Fourier transform and inverse Fourier transform are adopted in the coding process. The principle of the coding is to introduce a phase function into the reconstructed wave function of a dot-matrix hologram and record a new hologram. As the result of the coding, the new hologram not only preserves the pattern of the original dot-matrix hologram but also has 3D effect, which is resulted from the phase distribution on the hologram plane. Theoretical analysis and experimental results are presented.

Diffractive composite spatial code is a novel concealed optical code. It use diffractive micro-gratings matrix as carrier of diffractive composite spatial code. When diffractive micro-gratings matrix is lighted with monochromatic plane wave, diffractive composite spatial code appears. With the aid of specific recognizer, meanings which diffractive composite spatial code represents will be read out. Coding principle and design ofdiffractive composite spatial code are introduced in details in this paper. Detecting technology of this code is explored, too. The analyzing indicates that the method of recognizing of diffractive composite spatial code is unsophisticated and feasible. These characteristics are very important and useful in security of document, bond and even web.

The parameters used for recording 3D rainbow holograms are analyzed theoretically. The analysis indicates that the object distance in recording Fresnel hologram is a key parameter for diminishing field curvature and image blur due to wavelength spread and extended source size. To obtain sharp image under extended illumination, the object distance must be reasonably large. The experimental results verify the theoretical analysis.

Exposure and frequency characteristics of holograms obtained by the method of photo structural transformations in chalcogenide vitreous semiconductors have been studied. The maximal values of diffraction efficiency and sensitivity have been determined. The kinetics of isothermal erasure of holograms has been studied. The presence of residual holograms after a long erasure has been observed. Their diffraction efficiency is up to 20% from the initial value. The Bunsen-Roscoe's law is only observed at the ? = 1% at the recording of holograms by the method of photo structural transformations in chalcogenide vitreous films.

Sub-wavelength gratings could function as polarization components, such as wave-plates and polarized beam splitters. Furthermore, gratings in resonate regime could act as achromatic wave-plate. Here, an achromatic quarter-wave plate of a submicrometer grating with sinusoidal profile is designed based on diffractive optics. Rigorous coupled wave theory (RCWT) was used to analyze the subwavelength grating made on photo-resist in ambient air. Design of a broadband form-birefringent phase retarder for 400nm to 800nm visible region is discussed. A sinusoidal sub-wavelength grating with good properties was designed. Its phase retard maintains at about 90° and maximum deviation is about 15%, which approaches normal binary waveplate.

In this paper we present the design and development of volume holographic lenses for white light imaging and solar energy concentration. Details of design analysis and process of manufacturing of these lenses on dichromated gelatin is also given.

We propose a model for the stitching errors in the phase mask, that allows computing the near field of diffraction. We show that the noise field associated to the stitching errors has some periodicity, which can be imprinted into the fiber Bragg gratings resulting in sidelobe noise in the spectrum. This noise effect varies as a function of phase mask-fiber spacing.

In micro-optical elements design, in order to achieve an optimal performance and reduce the undesired background optical system noise, multilevel phase-only micro-optical elements and/or continuous-relief structures are required. The multilevel and continuous relief structures can be fabricated by multiple exposures through a set of binary masks, electron-beam direct writing, laser-beam direct writing and grey scale masks. For mass production of cost-effective monolithic micro-optical elements, the high-energy beam-sensitive (HEBS) glass offers an opportunity to generate a grey-scale mask for analogue 3D surface relief structures. In this paper, a negative-tone inorganic-organic hybrid SiO2/TiO2 glass is investigated for the fabrication of refractive and diffractive micro-optical elements. The sol-gel material enjoys an advantage over the conventional photoresist based fabrication techniques due to its single step etching-free process.

A novel genetic algorithm (GA) with a Lamarckian search is proposed for the design of the multiplexed computergenerated hologram (MCGH) with polygonal apertures. The Fraunhofer image of the new MCGH is computed by coherent addition of the subhologram subimages. The subimages are obtained by multiplying the fast Fourier transforms of the subhologram transmittance distributions by layout coefficients computed with the Abbe transform. The division into polygonal apertures is the same for all cells, and defines the polygonal layout of the cells. In our preceding designs of the MCGH with polygonal apertures, only the subhologram transmittances, but not the polygonal layout of the cells, were optimized with our iterative subhologram design algorithm (ISDA). In this paper, we optimize for the first time the polygonal layout of the MCGH cells with a novel GA. For fabrication by e-beam lithography, each cell is composed of a number of stripes. Each stripe is divided into some trapezoidal apertures, which can (i) take a number of different shapes and (ii) belong to a number of different subholograms. The number of possible polygonal layouts for the cells therefore is huge and equal to 264 = 1.85 × 1019 in the case of a MCGH with five subholograms. Each possible layout is coded as a chromosome of bits. Our novel GA performs crossovers and mutations. However, differently from the classical GA, our new GA also uses a Lamarckian search based on a gradient descent, and rapidly determines the optimal polygonal layout for the MCGH cells.

Sol-gel process is for more than one decade an interesting way to synthesize inorganic-organic composites under a soft chemistry route. Recently a process for the fabrication of self-developing diffractive optical elements has been developed. The inorganic part of the molecule was an alkoxysilane that reacted via hydrolysis and condensation reactions at room temperature, thus leading to a gel. The mild conditions under which the inorganic part of the material was prepared are compatible with the presence of an organic moiety, a methacrylate function. The organic network was produced via spatially controlled UV illumination using amplitude masks. Surface relief gratings were obtained via this photochemical step ; generation of relief resulted from mass-transfer by diffusion and gradient of surface free energy. No etching process was required. Although the hybrid sol-gel material was assumed to perform along the same lines as the one involving all-organic photopolymers, the influence of the inorganic moieties on the photopolymerization of the methacrylate function remained unknown. Characteristics of the photopolymerization process taking place in hybrid sol-gel materials were investigated by UV and FTIR spectroscopies. Besides the study of the organic network, NMR investigations led information relative to the inorganic network formation during the sol ageing. The whole results provide insights into the influence of the temperature during the photochemical step. Relief gratings generated under various conditions and for a large scale of spatial frequencies are presented. Sinusoidal to almost binary profiles were obtained in a one-step process.

Organic materials are of increasing interest for optical devices, especially in applications based on quadratic optical non linearities. In this context, we have studied photopolymerizable mixtures doped with non linear optical push-pull chromophores. The doped photopolymerizable films are poled with a static electric field and polymerized with a spatially controled irradiation in order to freeze the orientation of the chromophores in the desired areas only. The temporal stability of the chromophore orientation is checked by second harmonic measurements. The photopolymerizable system was chosen by taking into account the possibilities of microstructuration under visible illumination. This property was demonstrated by recording permanent thick phase gratings. Simultaneously, optimization of the polymer matrix from the viewpoint of chemical composition, conditioning and functionalization of the chromophore was performed in order to improve the stability of the chromophore orientation. Formulating of the material requires a fair knowledge of the coupling between photochemical conversion, mass transport, stiffening of the polymer matrix. Photostructuration together with stable non linear optical properties allows now to consider realistic applications.

It is shown experimentally that light emerging from two pinholes, after passing through two diffusers having same correlation properties but moving in opposite directions with same linear speed, is cross-spectrally-pure light. It is found that the visibility of the interference fringes is related to the average diffuser surface roughness

Diffractive optics is a rapidly developing branch of optics involved computer generated holography, kinoform technology, microelectronics and microfabrication technology. Fabricating some diffractive optics through optical lithography is an effective method. For optimizing lithography process of manufacturing diffractive optics, surface profiles of deep relief gratings are simulated in this paper. Different photoresists are used in the simulations, and simulation results are discussed.

The photopolymeriable gelatin (PPG) system we have studied comprises a mixture of acrylamide (AM), N,N'-methyknebisacylamide (BAM), triethanolaimine (TEA), methylene blue and gelatin. After wet processing, there is a thin layer of white fog, which results in the image noise of fabricated hologram. The factors which influence the noise in PPG system were studied in detail. They include monomer concentration ratio, TEA concentration, exposure energy and processing condition. The optimal condition that attributes to the lowest noise of PPG system is: (1) AM:BAM 30:1; (2) TEA%1%; (3)28°C of the washing temperature in the post-processing.

In the field of precision engineering, the demand for high resolution and accuracy in micro positioning and alignment is increasing. By superimposing a pair of specially coded 2-d gratings, the precise alignment between two gratings can be achieved. Based on diffraction theory, the effects introduced by several kinds offabricating and installation errors of the gratings are analyzed numerically in this paper. It is found that such grating alignment system has the function of reducing output error to an order of magnitude by averaging the fabricating errors. It's also found that varying the gap between the two gratings causes little effects on the output error and that the root-mean-square error of the output intensity increases linearly with the in-plane relative rotation angle between the gratings in small angle range.

A new red sensitiver holographic recording material has been studied by our group. The composition of the material is as follows: polyvinyl alcohol as binder, acrylamide and methylene bisacrylamide as monomer, methylene blue as sensitizer, triethanolamine as electron donor and other additive reagents. We get the optimum recipe through many tests. By adding other reagents that were designed by us, we obtain a high quality red-sensitive holographic recording material. The diffraction efficiency of transmission holographic grating is up to 95%, when the exposure energy is 3mJ/cm2. The post-processing is simple, the hologram has high diffraction efficiency, high signal-to-noise ratio, and excellent environmental stability.

In this paper, we present a new technique for adjusting and controlling the playback wavelength of Lippmann holograms recorded in methylene-blue sensitized dichromated gelatin (MBDCG). During the preparation of photosensitive layer, a water-soluble organic reagent, acrylamide is added homogeneously into our optimum MBDCG recipe as preswelling reagent. It will be dissolved completely into water during the postprocessing procedure and result in the uniform shrink of the fringe planes of reflection hologram, which will makes the playback wavelength shift relatively to shorter wavelength. This method can be applied to adjust the playback wavelength of reflection hologram quantitatively by changing the concentration ofpreswelling reagent.

In this paper, based on the photosensitive characteristics of a photopolymer recording material — Photoetching Cellulose Film (PCF), some effective post-processing techniques such as delay-development, ultraviolet (UV) uniform post-exposure, and chemical etching development, are investigated to increase the diffraction efficiency and relief depth of PCF micro-optical and holographic elements. The delay development technique can obtain an enhancement factor of more than 50%, while both the UV post-exposure and chemical development techniques can achieve up to 100% enhancement factor.

Digital implementation of fractional Fourier transform hologram (FRTH) is studied. From the definition of fractional Fourier transform (FRT), its discrete form is obtained and then a fast FRT algorithm is generated based on fast Fourier transform (FFT). Therefore, with the algorithm whose numerical efficiency is equal to the FFT, FRT can be quickly calculated and moreover FRTCGH can be efficiently encoded and reconstructed. The digital implementation for FRTH can lead its advantages, such as flexibility of fabrication and variation with recording system parameters, to expanding its application fields in FRT and holography.

Based on the analysis of phase aberrations in high power laser system, the phase corrector plate is presented to correct the static phase aberration. It can greatly improve the performance of the focal spot and is regarded as the suitable supplement of adaptive optics. In this paper, the performance of phase corrector plate, both continuous structure and multi-steps structure, is analyzed and simulated. The effect of misalignment between the phase corrector plate and the laser beam on the focal spot is also presented and simulated.

An effective method to accurately calculate sidelobe intensity for phase-shifting apodizers of three or more portion is presented. With this method, complete optimization can be performed in order to seek the optimal parameters of the apodizer. Optimization results show that it is not always the case that we should apply as more phase zones as possible due to the great loss of central peak intensity ratio. The reason why central peak intensity ratio drops greatly with increasing number of phase portions is also explained.

Large primary mirrors for optical telescope are usually interferometrically tested using null correctors. In fabrication of primary mirror, the optical surface is polished to precisely match the wavefront generated by the null corrector. The final shape of the primary mirror will be incorrect if a flawed null corrector has been used.In this paper a new test to certify null corrector was designed and implemented that uses small computer—generated holograms (CGH) fabricated onto flat substrates. This test solves the difficult problem of verifying the accuracy of the null correctors. A new technique for hologram fabrication has been explored for this application. A laser writing machine was built for fabricating these patterns onto flat substrates. The null corrector tests the hologram exactly as if a real mirror is to be measured. The use of hologram to test the null corrector is surprisingly simple. The CGH is positioned at the paraxial focus ofthe mull corrector. Once the CGH is near the correct position, the shape of the fringes in the interferometer is used to align the hologram. Since the CGH appears to the null corrector to be a complete primary mirror with correct shape, the corrector can be tested exactly.

A new tunable optical encoder/decoder structure based on holographic optical processor is proposed. The simulation experiments have been accomplished and a part of typical results are given in this paper. In contrast to the previous structures reported in the literature, the new structure has greatly reduced the hardware complexity, the cost and the power loss. It is easy to integrate.

In this paper, we propose an application of the mutually pumped phase conjugation to the all-optical connection switch and present the two type of the bi-directional cross connector with the photorefractive crystals, the polarized beam splitters and the half-wave plates in terms of the control method. In the type 1 connector, the bypass mode or the exchange mode can be selected by the external control beam whose polarization is orthogonal with those of the signal beams. In the type 2 connector, these modes can be controlled by rotating the polarization of the signal beams. We give the basic experimental result of these connectors with BaTiO3 crystals and Ar+ laser, and discuss about the results.

Volume holographic gratings and two-dimension periodic microstructures in azodye-doped polymethylmethacrylate were fabricated, respectively, by interference of two coherent beams of a femtosecond laser and by interference of three coherent beams of a nanosecond laser. The volume holographic gratings consist of two parts, surface relief gratings on both surfaces and refractive index modulated volume gratings in the interior of the polymers. The diffraction efficiency ofthe first-order Bragg for the gratings was estimated to be 91%. In the experiments for interference ofthree beams, the period of two-dimension periodic microstructures was changed by adjustment of the angle between the three writing beams. Experimental results showed that two-dimension periodic microstructures with O.69-µm period were formed on the surface ofpolymer samples.

Bessel beams are a special class of diffraction-free solutions of the wave equation which are of practical interest, for example, in precision alignment, laser machining and laser surgery. Therefore efficient methods for the transformation of a Gaussian laser beam into a Bessel beam are needed. We design and fabricate computer generated holograms(CGH) to generate this Bessel beam. Designed CGH is recorded onto the photopolymer which is used as a volume hologram material making CGHOE(computer generated holographic optical element). The principle of the CGH and the propagation characteristics of the Bessel beam are explained. The binary mask designed for generating Bessel beam is copied on photopolymer by the contact copy method. The axial intensity is measured for the beam propagation distances. The propagation property and the intensity profile of the Bessel beam are analyzed.

We have studied PRCM as a basic device that could achieve a free-space optical communication with the spatial parallelism using mainly photorefractive crystal and four-wave mixing technique. The asynchronous PRCM, which is newly introduced in this paper, has the diffraction grating generated by two control beams independent of the signal beam. Thus, the signal is transmitted at the velocity of light and can be branched with no delay from the multiple nodes connected on the transmission bus line. We also propose a new two-way communication device, to which double phase conjugator technology was applied, as opposed to the one-directional device of optical signals from the transmitting side to the reception side. We conduct a basic evaluation on the branching and transmission characteristics of signals at the spatial optical switch element.

A photopolymerizable system sensitive in the 450-550 nm range is proposed in which thick phase holograms are recorded in situ through polymerization and diffusion processes. Three applications are presented. i) Multiplexed holograms were created with a view to optical edge extraction filtering. Several slanted fringe transmission gratings were recorded in the same location with less than 0.5° changes of the slant angle and 0.1 ?m of the fringe spacing. Diffraction angles were not affected by shrinkage of the polymer layer that occurred during the successive exposures. By optimization of the recording schedule, it was possible to obtain the same fair diffraction efficiency for each grating at the expected angle, reading them simultaneously at normal incidence. ii) Taking advantage of the two glass plates laminating the emulsion, transmission and reflection gratings with fringe spacings lower than the incident wavelength were recorded with a view to fabrication of substrate-mode diffractive elements. iii) Binary amplitude elements with pixel size of 20 ?m were duplicated by imaging in the polymerizable system, giving rise to thick phase holograms. The diffraction efficiency and the quality of the reconstructed image were studied as a function of the recording conditions.

The diffraction of volume holographic gratings follows the Bragg law, and narrow wavelength selectivity and angle selectivity can be achieved with certain thickness of hologram. Multiple volume holographic gratings formed in Fe : LiNbO3 have high diffraction efficient and stability performance, which can be used for compact dense multiplexer/demultiplexer (MUX/DMUX). In this paper, we identify that it is feasible to record 16 volume holographic gratings by a special recording ways. The calculated results show the insertion losses and crosstalk at 1 .55µm waveband with channel separation 0.8nm is 0.66dB and —26dB respectively.

A CMOS IS (image sensor) has been widely applied in the multimedia field due to its unique features. One application of the CMOS IS in the microimage processing field is presented. An electronic eyepiece, mainly incorporating optical lens and a CMOS IS, is developed to digitize an optical image, process the digital signals and transmit them to a processor (i.e. computer). The digitized images are displayed in real time and stored off-line for post-mission analysis. An algorithm to process the image is adopted to extract features after the preprocessing operation. In this paper we will describe the system, introduce the structure of eyepiece and discuss the preprocessing technique. Finally some results of feature extraction are given. The system has been applied in the microimage processing field and the availability has been verified.

Transmitting optical system was part of"maneuverable type Carbon-Dioxide atmospheric Laser Communicator", which consists of Carbon-Dioxide laser, acousto-optical modulator, focusing lens, collimating lens and transmitting antenna. Ground-to-air communication distance up to 15km, error bit rate no more than 10-9. Image and speech can be transmitted separately with half duplex. Method for design major optical devices of ground-to-air laser communication transmitter, such as laser, optical lens, modulator and transmitting antenna was analyzed in the paper. The principle technical index of acousto-optical modulator and Cassegrainian antenna which determine decisively to transmitting optical system were detailed calculation. Experiment curve of acousto-optical modulator with germanium material versus carbon-dioxide laser beam, for instance, modulation bandwidth, diffraction efficiency and modulation linear was measured. At last, gain and efficiency of reflective Cassegrainian antenna were explored.

Optical fiber communication is gradually replacing the traditional cable communications because of it's high speed and high anti-interference advantages. The optical fiber LAN (local area network) has already been in application recently. This paper introduces a optical fiber LAN build in a four-floor building. The advanced devices such as optical exchange board, fiber-optic LAN adapter are used in the optical fiber LAN. These ensure the LAN high speed, high reliability and high anti electromagnetic interference. This optical fiber LAN has already been applied by Shanghai Funeral and Interment Bureau.

To make stereo and novel presentation is the target of optical display. By means of 3D restoring vision, animation, color effect and sound effect, emulation window can make the audience feel personally on the scene. Composed of special plating film glass, optical element, electronic parts and mechanical device, which are optimally designed and assembled, emulation windows presents the audience with realistic, interesting and novel vision. Basing on the feature of the sightseeing tunnel of Huangpu River and the general tunnel, we produce the emulation window of Huangpu River's tunnel. With this device, people feel that they are taking the bus, which is wandering, in the phantasmagoric tunnel and the road is endless.

In this paper, we analyse the principle of fiber Bragg grating anay as en-/de-coder and its realizing method. Then, an improved scheme, which can heighten data rate of single channel in this OCDMA system, is put forward by us. Furthermore, this scheme additionally possesses the convenience ofvariable bit rate service.

In this article, the crosstalk produced in optical node and its accumulations in all-optical system are analyzed. Furthermore, the influence of both optical switch insulation and the input signals power difference on system BER are calculated. From the simulation, the following conclusions are drawn: (1) non-ideal character of optical switch insulation is the main reason for producing crosstalk; (2) equalizing the optical power before the optical switch has better effects than afterwards.

Based on spread spectrum signals detecting technology, a kind ofsoftware capture method ofspread spectrum signals is presented. in this paper. A kind of 2-D signal capturing method is advanced which combines parallel pseudorandom-code (PN-code) phase and capturing of carrier frequency, as a result, the capturing time is shortened greatly. The method is used in this system by which the energy is accumulated to improve the signal-to-noise ratio (SNR) ofinput-signals, consequently improve the detection performance. The working principle and overall structure of the capturing system is introduced. The capturing structure model and mathematical one, the acquisition algorithm and realization, the design of parameters are discussed in detail. The possibility of the system has been verified by experiments and performance analysis.

This paper presents a new way for making circular hologram gratings with high-density and equidistance, namely to use reflection interference formed by cone mirror to obtain circular interference with equal fringe spacing. The intensity distribution of interference field of reflection formed by cone mirror and the method for recording hologram gratings are given. The author suggests that this way for fabricating circular hologram gratings will find extensive use in optical testing and fiber-optic devices (such as DWDM and DBR).

After exposure and processing, the Cr6+ ion in dichromated gelatin (DCG) is reduced to Cr3+. The unexposed Cr6+ is washed out by water and , the gelatin cross linked with Cr3+. Since the density distribution of Cr3+ is proportional to the exposure of light, distribution of Cr3 will be sinusoidal. Meanwhile, the ions or molecules of other materials are distributed uniformly in a certain range around Cr3+. Therefore, the distributions of positive and negative charges will be unequal, and an electric field will be induced inside the medium of volume hologram in macro-scale. The intensity of such electric field is calculated basing on this mechanism. and it is found to be considerably strong.