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A photorefractive hologram can be fixed locally under a temperature nonuniform field by CO2 laser heating the LiNbO3. Here, on the basis of analyzing the relationship between the fixed space-charge field amplitude Esc and the fixing temperature Tf, two parameters, the localization coefficient Ψ and the average space-charge field amplitude Escave, are defined to evaluate the fixed local photorefractive hologram by CO2 laser heating the LiNbO3. The same analysis also can be used when the boundary conditions and the laser beam profile are changed. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 89–93, 2000. [ABSTRACT FROM AUTHOR]

Based on Moharam's field modulation function and the coupled-wave equations, exact analytic straight and parametric expressions are deduced for the steady state of dynamic two-beam coupling with any constant values of light intensity modulation and light excitation efficiency. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 278–283, 2000. [ABSTRACT FROM AUTHOR]

The Talbot effect of a grating under ultrashort short-pulsed light illumination is analyzed from its Fresnel diffraction equation. We find that the Talbot self-imaging effect gradually diminishes when the full width Δτ at half maximum of the incident ultrashort laser pulse decreases. If Δτ is within a few tens of femtoseconds, the self-imaging effect disappears. We note that the maximal value of the sharp peak of the intensity distribution at the first Talbot distance increases steadily along with the increase of Δτ. Therefore, by using this phenomenon, the width of an ultrashort laser pulse can be measured roughly. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 184–187, 2000. [ABSTRACT FROM AUTHOR]

The transient interaction between a refraction index grating and light beams during simultaneous writing and thermal fixing of a photorefractive hologram is investigated. With a diffusion- and photovoltaic-dominated carrier transport mechanism and carrier thermal activation (temperature dependent) considered in Fe:LiNbO3 crystal, from the standpoint of field–material coupling, the theoretical thermal fixing time and the space-charge field buildup, spatial distribution, and temperature dependence are given numerically by combining the band transport model with mobile ions with the coupled-wave equation. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 372–376, 1999. [ABSTRACT FROM AUTHOR]

In this article we develop a new morphological image processor. In this processor, the input image and interconnection configuration are invariant, and feedback is not necessary. This processor can implement various structuring element morphological image processing functions. It can be implemented by a compact optical weighted interconnection module and the table-lookup threshold technique. Experimental results are also given. [ABSTRACT FROM AUTHOR]

Based on the quadratic residue number system (QRNS), a novel optical matrix-vector multiplication is proposed. Complex number multiplication has higher parallelism than other algorithms. If the residue number is binary encoded, this multiplication can be easily implemented with a multichannel incoherent optical correlator. [ABSTRACT FROM AUTHOR]

The optical set-up for a (2,L) SW-banyan network, which is based on polarizing beam splitters and ID phase spatial light modulators, is proposed and demonstrated, and its corresponding routing control for the routing path between any source-destination pair has been discussed. The proposed optical setup consists of only optical polarization elements, it is compact in structure its corresponding energy loss and cross talk an" low, and its available number of channels is high. [ABSTRACT FROM AUTHOR]

Based on the concept of urea coding, a 2D grayscale morphological processor module is developed by the integration of an optical connector and a PROM device. It is shown that the technique is compact in construction, simple to fabricate, and insensitive to environment. [ABSTRACT FROM AUTHOR]

We demonstrate a new approach to achieve optical shuffle interconnection by employing a photorefractive crystal plate in which some required holograms have been recorded and fixed in terms of holographic phase grating. The processes of beam recording, fixing, and reproduction art, described, and an implementation scheme for 1D and 2D shuffle is also proposed. The results of proof-of-principle experiments in one and two dimensions are also presented. [ABSTRACT FROM AUTHOR]

Based on programmable polarization-optical neighborhood interconnection, which is a stacked integration of rotatable crystal plates for beam splitting the controllable wave plates for polarization direction controlling, a kind of morphological processor with real-time programmable structure elements is developed. It is compact in structure and effective as well as stable in performance. [ABSTRACT FROM AUTHOR]

In this article, one-rule symbolic substitution is introduced to process 2D pattern logic. All the 16 possible logic gates of two input variables are designed. By using a combined system of a multiimaging unit and an optoelectronic morphological unit with two independent input planes of the control pattern and the input patterns, all the logic functions can be achieved by simply programming the control pattern. Experimental results are presented. [ABSTRACT FROM AUTHOR]

The Hartline model is an important neural network model which reveals the lateral inhibition in neural systems. In this article an opto- electronic architecture is proposed for implementing the Hartline model, in which an incoherent optical convolutor is used for the realization of the convolution operation and a polarization-coding method for the representation of the connection weights in the Hartline model. The subtraction is performed by electronics. Preliminary optical edge-enhancement experiments for two-dimensional images illustrate the versatility of the network. [ABSTRACT FROM AUTHOR]

In this Letter we propose complex modular multiplication of two N-bit negabinary complex numbers by adopting digital partitioning and weighting-shifting techniques. The module (-2)N - 1 is introduced for its simple arithmetic. Both complex numbers are treated as two N-bit negabinary real numbers. All four real numbers are decomposed into several short bytes; a corresponding complex product modular (-2)N - 1 is achieved by cyclic convolution. The subtraction in complex multiplication is converted to addition by weighting shifting. The algorithms can be implemented in a fully parallel manner, especially for optics. Both pre- and postprocessing are simple. The proof-of-principle experiment is performed by an incoherent optical correlator, and results are given. [ABSTRACT FROM AUTHOR]

A compact packaging optical crossbar network is proposed in the article. It is based on a polarization multiplex technique. This compact packaging crossbar network is easy to assemble and insensitive to environmental disturbance. We also construct an optical HIPPI interconnection system. [ABSTRACT FROM AUTHOR]

The optical implementations of a 2-D neural net with a third-order interconnection for image quadratic associative memory are reported. Two types of incoherent optical systems, based on multiple imaging and correlation, are used. In particular, a compact-encoding method, which can greatly reduce the size of the interconnection tensor, is also proposed. The experimental results are given. [ABSTRACT FROM AUTHOR]

An accumulative recording scheme capable of enhancing diffraction efficiency effectively during nonvolatile holographic storage in LiNbO3:Fe:Mn crystals is proposed and experimentally demonstrated in this paper. The main idea of this new holographic recording schedule is that, during every red-beam recording interval, an ultraviolet light is used to excise more electrons to a shallower center for the next faster and higher recording. After sufficient accumulation of the space-charge fields developed in a deeper center, it is possible to gain a high diffraction efficiency of the finally fixed hologram. The experimental results demonstrate that the finally fixed diffraction efficiency is enhanced by about 31% compared to the conventional recording schedule. No additional equipment is needed in this method, and it has potentials for applications. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 423–425, 2002. [ABSTRACT FROM AUTHOR]

We use a normalized pattern spectrum to construct an image feature vector. In addition, we set up an optical learning vector quantizer to execute real-time image feature vector classification. On the base, shift and rotation-invariant pattern recognition can be achieved. [ABSTRACT FROM AUTHOR]

A new binary-encoded matrix-matrix multiplication architecture based on correlation by shadow casting is presented. It can perform a binary-encoded matrix-matrix multiplication in a fully parallel manner to get the mixed-binary output matrix in the focal plane of the lens. Both the advantages and the disadvantages of the proposed architecture are carefully discussed. The proof-of-principle experiments demonstrate the effectiveness of the proposed architecture. [ABSTRACT FROM AUTHOR]

An optoelectronic architecture is suggested to perform local cellular logic. A polarization coding technique along with the electronic substraction and thresholding techniques are developed to complete the operations with both positive and negative interconnections. Experimental results of the Laplacian operator for edge enhancement and their numerical simulations are given. [ABSTRACT FROM AUTHOR]

Based on dual-rail spatial coding, in this article a self-programming optical logic concept is proposed. The self-programming is formulated by different coding of input images. Thus all 16 binary logic operations can be realized optically in parallel. Experimental results are demonstrated. [ABSTRACT FROM AUTHOR]