Integration of InGaAsP/InP optoelectronic bistable switches with a function of optical erasing

An OE-PPM (optically erasable photonic parallel memory) that is an array of 10*10 optoelectronic bistable switches with an optical set and reset function has been fabricated successfully, and set and reset operation with light signals has been demonstrated. The switch consists of a heterojunction phototransistor (HPT) and a light-emitting diode (LED), and the reset operation is performed by an additional reset HPT. The minimum reset power is 1.6 mu W at a bias voltage of 0.9 V, and the set power and the dissipation current at the same bias condition are 3.4 mu W and 200 mu A, respectively. These values are thought to be low enough for array operation. A light pulse with a width of 10 ns was able to set or reset the switch, though the set and reset powers were increased to 547 and 406 mu W, respectively. The dominant factor that limits the speed of set and reset operation is thought to be the response time of the HPT.<>