Bistable opto-optical switches with high optical gain based on n-i-p-i doping superlattices

We report on optical logic gates and bistable opto-optical switches with high gain operating at very low threshold power. These devices are ‘‘smart pixels’’ composed of n-i-p-i threshold switches and modulators. Very high values of 3×105 for the opto-optical gain (‘‘fan-out’’) and extremely low switching powers of less than 500 pW in combination with a broad hysteresis width of 200 pW are obtained. The switching power, the width of the hysteresis, and the opto-optical gain are all externally adjustable. The observed contrast ratio of 4.6 for the output signal corresponds to an optically induced voltage swing of 2.5 V.