High‐modulation depth modulator based on double‐layer graphene with a low bias voltage

Abstract

An efficient modulation can be obtained by graphene due to its outstanding light-matter interaction, and many kinds of modulators based on graphene have been studied during the last couple of years. However, there still exist unsolved issues in graphene-based modulators, such as how to make a balance between modulation depth and modulation bandwidth. This work proposes a reflective modulator with relatively high-modulation depth and wide working bandwidth. The proposed modulator has a simple five-layered structure of graphene–silica–graphene–silicon-metal. They use an effective method of finite element method to simulate the performance of this modulator, and obtain a modulation depth of 96% with a low bias voltage of ∼4 V. Furthermore, they calculate the modulation speed by the equivalent circuit method, and obtain the maximum modulation speed of about 25 kHz and a wide broadband of 72 kHz from theoretical analysis. Therefore, this high-performance modulator provides an effective method for terahertz communication devices.