▎ 摘　　要

In order to overcome the challenge of obtaining high modulation depth due to weak graphenelight interaction, a graphene-on-silicon nitride (SiNx) microring resonator based on graphene's gate-tunable optical conductivity is proposed and studied. Geometrical parameters of grapheneon-SiNx waveguide are systematically analyzed and optimized, yielding a loss tunability of 0.04 dB mu m(-1) and an effective index variation of 0.0022. We explicitly study the interaction between graphene and a 40 mu m-radius microring resonator, where electro-absorptive and electrorefractive modulation are both taken into account. By choosing appropriate graphene coverage and coupling coefficient, a high modulation depth of over 40 dB with large fabrication tolerance is obtained.