Abstract

We reported the first digital all-optical circuits using steady-state continuous-mode optically bistable devices which can be optically biased and held close to switchpoint and which give an incremental change of output sufficient to switch succeeding elements.^1,2 These circuits have been demonstrated using cascadable elements constructed, respectively, from InSb (using electronic nonlinearities) and ZnSe refractive interferometric devices. This approach derives from the original (1979) observations of steady-state optical bistability³ and gain in an optical transphasor.⁴ Cascadability, fan-out, and fan-in are essential elements of an all-optical digital parallel computer in which, in the first instance, the opportunity provided for massive parallelism through the simplicity of optical interconnects is seen as one of the prime routes to be investigated toward realizing very high logic rates. With the requirement for restoring logic that there be gain in addition to regions of valid logic-0 and valid logic-1, we show that for digital optics this can be readily achieved by the technique of hold-and-switch. The use of off-axis address for the holding (or optical bias) and signal beams allows digital circuits to be constructed with the required features of restoring logic which can be infinitely extensible given sufficient supply of separately holding beams which can be construed as the power supplies of ensuing circuit elements.⁵

© 1986 Optical Society of America