Highly efficient single-layer graphene electro-absorption modulator.

We propose a single-layer graphene electro-absorption modulator (EAM) with an angled waveguide sidewall. By utilizing the hybridization of the TM0 mode and the TE1 mode in the waveguide, the light-graphene interaction is enhanced. A modulation depth of 0.124 dB/µm and a figure of merit up to 25 are obtained at 1550 nm. Moreover, we show that the longitudinal electric field plays a significant role in making the optical absorption efficient, which indicates that modulation depth can be increased by enhancing the longitudinal electric field in modulators. This provides a promising solution for the future design of graphene optical modulators.