Abstract

From the starting point of mW-power infrared-driven digital optical logic elements working from nonlinearity of electronic origin, simple 2-element circuits were demonstrated with the capability of sub-microsecond cycle rates but with difficulties in fabrication of parallel arrays. Current work has therefore concentrated on devices made with thin-film coating techniques in which both conventional thermal evaporation and molecular beam deposited layers have been used. At comparable device diameter, operating powers are typically a few milliwatts, similar to the infrared electronic case. The early devices have shown sufficient stability to demonstrate 'hold and switch' circuits operating continuously so that the results of a processing operation can be stored. Gain of up to 10 has been typically observed but the available output signal limits subsequent switching speeds. Off-axis address ensures standard logic levels and thus a 3-element 'optical classical finite state machine' has been demonstrated to show restoring logic operation over many cycles as well as the necessary inversion function.

© 1988 Optical Society of America