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 highmodulation depth and wide working bandwidth. The proposed modulator has a simple five-layered structure of graphene-silica-graphenesilicon-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.

Field enhancement assisted graphene‐based microring modulator for high modulation depth

“…The single‐layer graphene absorption lies around 0.1 dB μm −1 , as a result very large interaction length is required to achieve 3 dB modulation. The graphene has little influence on the real part of the effective index, the development of phase‐tunable modulators have been designed with structures based on increased interaction of graphene with light [5]. With the aim to achieve higher electro‐absorption and electro‐refraction performance, waveguide geometries have been proposed to optimise graphene light interaction by placing graphene sheets close to the maximum of the electric field [6].…”