Modulation bandwidth improvement of III-V/Si hybrid MOS optical modulator by reducing parasitic capacitance
Hanzhi Tang, Qiang Li, Chong Pei Ho, Junichi Fujikata, Masataka Noguchi, Shigeki Takahashi, Kasidit Toprasertpong, Shinichi Takagi, Mitsuru Takenaka
Abstract
In this work, we numerically and experimentally examined the impact of parasitic capacitance on the modulation bandwidth of a III-V/Si hybrid metal-oxide-semiconductor (MOS) optical modulator. The numerical analysis revealed that the parasitic capacitance between the III-V membrane and the Si slab should be considered to achieve high-speed modulation, particularly in the case of a thick gate oxide. We also fabricated a high-speed InGaAsP/Si hybrid MOS optical modulator with a low capacitance using a SiO 2 -embedded Si waveguide. The fabricated device exhibited a modulation efficiency of 0.245 Vcm and a 3 dB bandwidth of up to 10 GHz. Clear eye patterns with 25 Gbps non-return-to-zero (NRZ) modulation and 40 Gbps 4-level pulse amplitude modulation (PAM-4) were obtained without pre-emphasis.