Keywords:Optical modulator, Franz-Keldysh effect
Silicon (Si) optical modulator is a crucial component for optical communication system. Si metal-oxide-semiconductor (MOS) type optical modulators have demonstrated high modulation efficiency owning to the large change of refractive index induced by the accumulated free carriers at the MOS interface. However, all the MOS type optical modulators work under the accumulation mode, which necessitate a large oxide capacitance, limiting the modulation bandwidth and energy consumption. In this study, we propose a III-V/Si hybrid MOS optical modulator based on Franz-Keldysh (FK) effect and carrier depletion effect. By combing these two effects together under negative bias, high modulation efficiency, large bandwidth and small energy per bit are achievable.