Spot Array Generator Research Articles

Dynamic holographic interconnects with analog weights in photorefractive crystals

A photorefractive interconnect system with coherently erasable synapses (PISCES) is described. Comparing holographic erasure by intensity and phase modulation of the writing beams, we find that the timeaverage technique is most amenable to system implementation. Calculations derived from a simple model of diffraction show that it is possible to find configurations that maximize the interconnection capacity. The PISCES includes Fresnel zone plates for spot array generation, amplitude and phase spatial light modulators based on liquid crystal technology, and detector arrays, in addition to the photorefractive crystal. Alternatives for each of these elements are described.

Iterative encoding of high-efficiency holograms for generation of spot arrays

An iterative discrete on-axis encoding method for computer-generated holograms (termed IDO encoding) has been developed. The binary IDO method employs simulated annealing to optimize the hologram phase delay and reduce sensitivity to fabrication tolerances. Computer-simulation results indicate that binary phase IDO encoding is capable of generating two-dimensional spot arrays with diffraction efficiencies larger than 70%. An experimentally fabricated hologram, designed to account for a 6% manufacturing hologram thickness tolerance, produced a 3 x 3 array of spots with 59% diffraction efficiency. The binary IDO algorithm can be employed to encode arbitrary images with twofold rotation symmetry.

Generation Of Large Spot Arrays From A Single Laser Beam By Multiple Imaging With Binary Phase Gratings

A simple technique for generating large (100 x 100+) arrays of uniform intensity spots of good contrast is proposed. One application of such spot arrays is as power supplies for optical logic devices in two-dimensional optical computing/switching architectures. This spot generation technique utilizes binary phase gratings both to produce small spot arrays (-20 x 20) and to multiply image them. Since the gratings need produce only small numbers of spots, the design computation and fabrication constraints are simplified. An experimental demonstration of this technique for an 81 x 81 array is presented along with a discussion of potential limitations.