Programmable coherent source arrays generated by spatial light modulators.

Programmable coherent source arrays are generated by using addressable liquid-crystal spatial light modulators and two-dimensional arrays of Fresnel lenses. The modulators used are an optically addressed liquid-crystal light valve, a matrix-addressed pixelated display, and two devices that have individually addressable elements with specially designed patterned electrodes. One such device has a transparent electrode patterned as a Fresnel zone plate array; the other is a gate array used in a hybrid implementation with a Fresnel lens array etched on a glass substrate. The operation of devices that use binary-amplitude and binary-phase Fresnel lenses is described, identifying programmable features, resolution limits, and applications.

Generation of programmable coherent source arrays using spatial light modulators.

We demonstrate and characterize arrays of coherent focused spots generated by writing multiple Fresnel zone plates on optically and electrically addressed modulators. The programmable parameters of the array are its size (number of generated spots) and the transmissivity and focal length of each lens. As expected, phase modulators have a better conversion efficiency than amplitude modulators do.

Binary phase Fresnel lenses for generation of two-dimensional beam arrays.

Two-dimensional arrays of mutually coherent optical beams are needed in holographic interconnections for both recording and reading gratings. We analyze the use and limitations of binary phase Fresnel lenses to generate beams for these applications. Two known techniques of ion beam milling and thin film deposition are compared to fabricate such lens arrays in SiO(2) and Si(3)N(4). Each lens in the 8 x 8 arrays has a 1.2-mm square aperture with a focal length of 20 mm. Diffraction of a single argon-ion beam into an 8 x 8 array of highly uniform coherent focused beams (with 12-microm spot size) was achieved by the lenses with an efficiency of approximately 30% (41% theoretical limit).

Implementation of a fast digital optical matrix-vector multiplier using a holographic look-up table and residue arithmetic.

The design and implementation of a digital (numerical) optical matrix-vector multiplier are presented. A Hughes liquid crystal light valve, the residue arithmetic representation, and a holographic optical memory are used to construct position coded optical look-up tables. All operations are performed in effectively one light valve response time with a potential for a high information density.