Ultrafast suspended self-biasing graphene modulator with ultrahigh figure of merit

A theoretical investigation of a suspended self-biasing graphene waveguide for electro-optical modulators is presented. The light-matter interaction can be enhanced by suspending the waveguide. For electro-absorptive modulation, the normalized modulation depth can be 0.54 dB/μm with a 3-dB footprint of only 1.5 μm2. The insertion loss is extremely low ∼ 0.002 dB, with the figure of merit of ∼ 2700. For the electro-refractive modulation, a 100% modulation can be achieved with much smaller π-phase shift length of only 18.0 μm. The modulators also show great potential for high-speed (∼ 559.2 GHz) modulation. The compromise between modulation speed and modulation efficiency is reduced significantly and the design is near-optimal to its fundamental limits. Moreover, a verification simulation by COMSOL is also given. This suspended graphene modulator can pave the way to practical high-speed, compact-footprint, and high-efficiency devices.