WAVELENGTH SELECTIVE OPTICAL LOGIC AND INTERCONNECTS

We describe a novel wavelength selective optical logic (WSOL) element which makes use of monolithically integrated wavelength selective optical input and output elements. Input optical signals are detected by photothyristors situated in an optical cavity which provides a highly selective response at a wavelength determined by the fabrication process. Output signals are generated by vertical cavity surface emitting lasers whose lasing wavelengths can also be specified during the fabrication process. We propose a vertical integration of these input and output elements which will be highly suitable for wavelength selective optical logic and wavelength selective optical interconnect applications. These devices can be fabricated to detect and emit within independently selected narrow wavelength ranges, at arbitrarily chosen positions across the wafer. The broad tunability range and the high wavelength selectivity of each WSOL device allows a large number of wavelengths to be used simultaneously while low crosstalk is maintained between nearby devices. As interconnects, the WSOL input and output elements will allow the information from many closely spaced wavelength channels to be coupled through a single optical fiber. As individual logic elements, WSOL devices are capable of completely optical logic operations at designer selected input and output wavelengths. The proposed circuitry is easily cascadable so that arbitrarily complex optical logic functions can be performed by WSOL devices in series. Several of the possible logic functions are described including OR and AND gates, an ADDER, and a FLIP-FLOP.