KEYWORDS: Computing systems, Waveguides, Optical interconnects, Free space optics, Standards development, Human-machine interfaces, Connectors, Switches, Local area networks, Free space
Optical interconnects for advanced computers have been postulated for the past two decades to obtain performance and reliability improvements over existing electrical interconnects. Optical interconnects have the potential for extremely high bandwidth, immunity to electromagnetic interference, elimination of radiated emissions, and lower costs. To date, this potential has yet to be realized. The ever increasing clock rates and interconnect complexity associated with emerging computer device technology as well as the increased emphasis on massively parallel processing may serve to hasten the implementation of optical interconnects into computer systems. This paper discusses some of the issues associated with the implementation of optical interconnects in advanced computer systems and presents the status of the U.S. Navy optical backplane interconnect system (OBIS) program.
The term "photoneuron" describes an electro—optic hardware element which
permits an optical implementation of the postulated information transfer
processes of the neurons in the human brain. The photoneuron provides
a dynamic activation and control mechanism for highly parallel computers
and permits immediate implementation of reconfigurable high speed
optical interconnects. The suggested method for interconnecting
processors in a photoneuronic network consists of embedded optical
fibers in composite materials to form optical backplanes utilizing
"smart skin" technology. This method eliminates the environmental
concerns and technological barriers posed by free space optics and
integrated optics, while providing a sound engineering approach leading
to the all optical computer. This paper briefly reviews the
physiological activity of neurons in the human brain. Optical analogies
for processor activation in neural networks corresponding to the nerve
impulse activation in the brain are then described. The paper then
suggests the utilization of optical signal parameters and encoding to
emulate the information exchange of neurotransmitters provided by first
and second messenger molecular activity across the synaptic
"connections" of neurons in the brain. This represents a departure from
most neural networks which dwell on threshold processor activation and
ignore the exceedingly complex molecular information exchange mechanisms
of the brain. Digital, analog, and combinatorial alternatives are
described.
A high degree of fault tolerance is required in both commercial and military fiber optic networks. Building fault tolerant physical layers for itultiport fiber optic systems is difficult because of the limited optical loss budget available and the limitations of electro-optic components including sources couplers and switches. This paper describes a fault tolerant fiber optic physical layer based on U. S. Patent 4 The concept permits the circumvention of faults in electronics power supplies or in optical fibers without the need for bypass switches. The fault tolerance is achieved through the use of a 1XN coupler with multiple photodiodes and fibers.
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