Joseph Shamir

Optical interconnection network using polarization-based ferroelectric liquid crystal gates

A polarization-based 4 x 4 optical interconnection network using surface stabilized ferroelectric liquid crystal (SSFLC) gates is demonstrated. The SSFLC gates are comprised of an SSFLC device sandwiched between two polarizing beam splitters. Optical crosstalk using these fast switching programmable devices can be limited to ~-20 dB/gate, which would allow 2-D interconnection networks to be fabricated with thirty-one input channels and 3-D interconnection networks with approximately 225 input channels.

Optical computing and the Fredkin gates

The use of optics to implement the Boolean logic functions traditionally used in conventional electronic computing is an active area of optical computing research. Many proposed optical implementations duplicate the configuration of electronic logic gates and hence may not optimally utilize the full benefits of optical techniques. We present here a new optical gate, the Fredkin gate, which may, in principle, be minimally dissipative (i.e., exhibit reversible logic) and whose response time may be limited in some implementations only by the duration of optical pulses (i.e., in the picosecond range). Such gates, which consist of three input and three output lines, can be programmed to produce a standard set of Boolean functions and appear well matched to the parallelism of optics. We present here a number of optical implementations of Fredkin gates and suggest ways of composing their interconnections to achieve combinatorial logic, circulating memories and generalized interconnects.

Dynamics of hologram recording in DuPont photopolymer

Several dynamical aspects of the DuPont photopolymer film HRF-150-38 for holographic storage are described. We study temporal aspects of exposure, exposure time, processing situations, and storage effect. The quantities studied are diffraction efficiencies, thickness changes, and Bragg angle. The experimental results are performed with an argon-ion laser at 514.5 nm.

Circular harmonic phase filters for efficient rotation-invariant pattern recognition

A generalized approach for pattern recognition using spatial filters with reduced tolerance requirements was described in some recent publications. This approach leads to various possible implementations such as the composite matched filter, the circular harmonic matched filter, or the composite circular harmonic matched filter. The present work describes new examples leading to very high selectivity filters retaining rotation invariance and reduced requirements on device resolution. Computer simulations and laboratory experiments show the advantages of this approach.

Massive holographic interconnection networks and their limitations

Fundamental and practical limitations to be encountered in the implementation of massive free space optical interconnects are discussed in detail, and some improved architectures are proposed. The long term optimum design uses currently unavailable large arrays of laser diodes. An interim solution, using available spatial light modulators, is shown to be capable of storing ~10(10) bits of information and performing ~10(11) interconnections/s.

Wave particle duality considerations in optical computing

The wave particle duality inherent in the propagation of light or particles can be exploited for energy efficient computing leading to energy requirement per calculation below kT. Although several reversible computers with similar characteristics were proposed in the past, only optical implementations can be made with the present technology.

Wavefront correcting properties of corner-cube arrays.

The performance of corner-cube arrays as pseudophase-conjugation wavefront correctors is investigated theoretically and experimentally. Hollow electroformed arrays and solid plastic arrays of corner-cube retroreflectors have been optically characterized and studied in a pseudophase-conjugate imaging system. The use of a collimating lens is found to improve dramatically the image quality.

High-efficiency rapidly programmable optical interconnections.

An array of optical Fredkin gates implemented by optically controlled waveguide couplers is shown to constitute a very efficient and versatile optical interconnection network with parallel addressing capabilities. The characteristics of the array are analyzed using linear algebra to indicate interconnect programming procedures. In terms of SNR this network is estimated to be comparable with previously proposed architectures. However, from many other aspects (light transmission efficiency, number of switching elements, speed, and fault tolerance) it has significant advantages.

Design for a massive all-optical bidirectional associative memory: the big BAM.

An optical bidirectional associative memory offering a potential of operating up to 10(6) neurons with 10(12) interconnections is described. Except possibly for input and output all operations are optical and parallel.

Flexible two-way optical interconnections in layered computers

Realisation de communications bidirectionnelles a grande vitesse adaptative flexible entre des couches optoelectroniques et une region de commande centrale a travers une colonne de lumiere. Analogie avec le systeme nerveux vertebral