Compact electro-optical programmable logic device based on graphene–silicon switches

Abstract

A compact electro-optical programmable logic device (PLD) which can provide any of 16 possible minterms of four Boolean variables on an optical signal is demonstrated in this paper. The presented structure is based on electro-optical graphene–silicon switches that consist of a Mach–Zehnder interferometer in which a few-layer graphene is embedded in silicon slot waveguide to construct phase shifters. A large effective index variation can be achieved by embedding few-layer graphene inside the slot waveguide which enables us to have a compact footprint. Our analysis shows that the presented PLD has a small footprint of 1.86 × 1.28 mm2. Any combinational logic circuit can be implemented by programming the proposed PLD. Here, the presented structure is programmed to work under three different modes including logical operations, two-bit adder, and two-bit comparator with the advantage of very fast switching among operation modes. Comparison with previous works shows that our design has a compact footprint, high extinction ratio, and low insertion loss with broadband spectrum for wideband telecommunication.