The design of graphene-based electro-absorption modulator

Abstract

The graphene-based silicon modulator can benefit from the outstanding optical and electrical properties of graphene which makes this kind of modulator a potential candidate for applications such as optical communication and optical interconnect which have strict performance requirements, like broadband operation, low optical loss, low-cost and high speed. In this work, a graphene-based high speed electro-absorption modulator is constructed. Firstly, a typical graphene-oxide-silicon (GOS) structure modulator with one-layer graphene is designed and simulated. The mode field distribution and single mode loss is simulated. Secondly, in order to improve the performance of the graphene-based modulator, the structure of the modulator is optimized. Instead of one-layer graphene, two layers are used. By adjusting the position of graphene in the structure of modulator, a graphene-oxide-graphene (GOG) structure modulator is designed. The structures of graphene layers on top of the silicon-based waveguide and graphene layers sandwiched between two silicon-based waveguides are designed, and the latter one is chosen because it has the advantage of stronger interaction between graphene and light field. By simulation, the extinction ratio of this proposed modulator is as high as 15 dB, and the modulation depth is about 93.3%. The operation bandwidth is calculated to be 52 GHz with low insertion loss of 1.55 dB.