Broadband graphene/hexagonal boron nitride modulators based on a Si 3 N 4 waveguide

For exploring a strong electro-optic effect from a graphene/hexagonal boron nitride (hBN) structure, here a comprehensive study for investigating the integrated broadband graphene/hBN modulators has been presented. Two representative configurations with a S i 3 N 4 waveguide were compared, focusing on optimizing the hBN thickness, waveguide width and height, and graphene size to balance their performances. It was found that 200 µm long devices with 65 nm hBN thickness allow for ∼ 80 G H z modulation bandwidth, 35.4 dB extinction ratio, and over 700 nm operation spectral range. Compared to the ridge S i 3 N 4 waveguide, the buried S i 3 N 4 waveguide was more suitable as an optical waveguide for the graphene/hBN modulator to obtain a large modulation depth of ∼ 0.17 d B µ m and a large operation spectral range from 750 to ∼ 1640 n m .