▎ 摘　　要

Graphene is a suitable material for high efficient optical modulator. However, the graphene-based modulator has a strong polarization dependence. Here a high performance polarization-insensitive graphene modulator is proposed by utilizing a mode conversion structure. Our modulator is not only CMOS-compatible but also improves the modulation performance of the TE mode that has weak light-graphene interaction in graphene-on-Si structure. The theoretical analysis of the modulator was performed. The device can operate at the spectrum of 1.5 mu m to 1.6 mu m with the extinction ratio of > 17d B, the insertion loss of < 5.7B for both modes, and the polarization-dependent loss of < 2.3d B. When the modulator operates at the center wavelength of 1.550 mu m, a low polarization-dependent loss of 0.6 dB is obtained. The 3dB modulation bandwidth is about 14.3 GHz based on theoretical calculation at the cost of 270 mu m device length.