F. A. P. Tooley

Challenges in optically interconnecting electronics

The challenges associated with the development of free-space optically interconnected electronics are discussed. These include finding an application for which optics offers an improved performance, developing optical transceivers, and developing suitable optics and mechanics. The main focus of the paper is the discussion of some novel approaches that smart pixels offer to increase alignment tolerance.

Nonlinear Optical Circuit Elements As Logic Gates For Optical Computers: The First Digital Optical Circuits

The first digital all-optical circuits based on intrinsic bistable devices have now been realized. Experimental results with two systems, InSb etalons and nonlinear interference filters containing ZnSe, are presented and discussed. These results indicate that a digital optical processor incorporating devices of this type would appear to be feasible.

Design of a symmetric self-electro-optic-effect-device cellular-logic image processor

A cellular-logic image processor was designed, constructed, and successfully operated by interconnecting two arrays of 128 symmetric self-electro-optic-effect devices. Design issues associated with the implementation of this free-space digital-optical system are discussed.

Design and implementation of a modulator-based free-space optical backplane for multiprocessor applications

Design and implementation of a free-space optical backplane for multiprocessor applications is presented. The system is designed to interconnect four multiprocessor nodes that communicate by using multiplexed 32-bit packets. Each multiprocessor node is electrically connected to an optoelectronic VLSI chip which implements the hyperplane interconnection architecture. The chips each contain 256 optical transmitters (implemented as dual-rail multiple quantum-well modulators) and 256 optical receivers. A rigid free-space microoptical interconnection system that interconnects the transceiver chips in a 512-channel unidirectional ring is implemented. Full design, implementation, and operational details are provided.

All-optical programmable logic gate

Experimental results are presented showing all-optical programmability and operation of a multifunction Boolean logic gate. All eight symmetric two-input logic functions have been demonstrated. Comments on the practical implementation and usage of this gate within an optical circuit are made.

InSb Devices: Transphasors with High Gain, Bistable Switches and Sequential Logic Gates

InSb etalons operated at 77 K and illuminated by CO lasers (5.5 pm) exhibit continuous wave (c.w.) optical bistability. A wide range of experiments have been performed to further the basic characterization of these devices and to demonstrate their various potential applications. The latter include signal amplification, modulation and, with external switching, the construction of logic gates. Two devices on a single etalon have now been coupled to form a simple all-optical circuit. New results have also been obtained with InSb at room temperature with pulsed CO2 lasers (10.6 pm).

Perfect-shuffle interconnected bitonic sorter: optoelectronic design

The algorithmic, electronic, and optical aspects of the implementation of a perfect-shuffle interconnected bitonic sorter are analyzed. The performance metrics such as the bit output data rate and the power consumption of the system are quantified. The sorting module is designed to demonstrate the parallel nonlocal interconnection of smart-pixel arrays and the use of optical-image control masks in a functioning information processor.

Cascadable digital optical logic circuit elements in the visible and infrared: demonstration of some first all-optical circuits.

The results of investigations into the feasibility of incorporating optically bistable elements into an optical processor are presented. Two forms of bistable device, etalons of InSb and interference filters containing ZnSe, have been used in the first experimental demonstrations of digital all-optical circuits. It is shown that cw optical bias beams may be used to hold logic gates sufficiently close to their switch point that the available signal gain allows one to realize indefinitely extensible optical logic. The results of such experiments are presented and the implications they have on the field of optical computing are discussed. It is concluded that parallel arrays can give significantly high rates of digital operations.

Optical design of a 1024-channel free-space sorting demonstrator

We describe the optical design of a free-space interconnect system to be used for a 32 x 32 sorting system. The system uses 4f imaging relays to connect two hybrid optoelectronic-complementary metal-oxide semiconductor chips. These relays are used to implement a perfect-shuffle interconnect necessary for the sorting algorithm to be implemented. The relay lenses are also used with patterned mirrors and polarizing elements to combine read beams necessary for the optoelectronic chips. Issues relating to the basic system design and the detailed design of the lenses and optomechanics are given.

Optical cellular logic image processor: implementation and programming of a single channel digital optical circuit

A diode-laser driven all-optical iterative processor has been constructed and tested. Results are presented showing operation equivalent to a single channel of the cellular logic image processor architecture. Functional features of the circuit include optically programmable logic, thresholding, and data synchronization. Essential elements such as cascadability, logic-level restoration, and data feedback have been demonstrated with the optical processor controlled by a conventional electronic computer. Serial processing algorithms for word recognition, comparison, full addition, and subtraction have been implemented. Comments on the reliability of operation and future plans for expansion are made.