Suspended Triple-Layer Graphene Modulator With Two Modulation Depths And Ultra-High Modulation Speed

The suspended triple-layer graphene modulator is firstly investigated theoretically. We find there appear two modulation depths for electro-absorption modulation. The light-graphene interaction is enhanced to its maximum by our designed waveguide structure. The highest modulation depth for electro-absorption modulation can be 0.834 dB/mu m, causing a 3-dB footprint of only 0.94 mu m(2). For electro-refractive modulation, there appear several 100% modulations with a much smaller pi-phase shift length of only 11.3 mu m. This modulator also shows great potential for high-speed modulation with a prediction value of 759.85 GHz, while the switch energy can be as low as 0.61 fJ/bit with low applied voltage. Moreover, the verification simulation by COMSOL is also presented, which shows very good agreement with our calculation results, and the figure of merit (defined as the ratio of modulation depth to insertion loss) of this modulator can be 2105. We believe these results can pave the way to design practical high-speed, compact-footprint, and high-efficiency devices. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement