Optical interconnections and optical digital computing based on the photonic parallel memory (PPM)

Abstract

We have proposed and fabricated a photonic parallel memory (PPM) which is an array of optoelectronic bistable switches. The switch consists of a heterojunction phototransistor (HPT) and a light-emitting diode (LED), and optical positive feedback from the LED to the HPT is the cause of bistability. In addition to the electrically erased PPM having only switches, an optically erasable PPM is also demonstrated. The optical reset function is attained by an additional HPT connected to the switch electrically in parallel. The memory operation of the PPM with functions of optical write-in, read-out, and erasing has been demonstrated. The minimum dissipation current of the switch was 130 μA, and the input optical power for set or reset was 3.4 μW or 1.6 μW, respectively. The light pulse with a width of 10 ns was able to set or reset the switch. The optical crossbar switchboard, the free-space reconfigurable interchip connections, and the parallel logic gates have been proposed based on the PPM.