High-bandwidth Si/In₂O₃ hybrid plasmonic waveguide modulator

A novel Si/In 2 O 3 hybrid plasmonic waveguide modulator was experimentally realized by using an asymmetric directional coupler (ADC), which consists of a silicon photonic and waveguide. All the cores are covered with silica layer, above there is metal–oxide–semiconductor (MOS) capacitor consisting In /HfO /Au layers. The Au layer sitting on top MOS works as top-electrode, while thin film covers sidewall contacts bottom-electrode. When bias voltage not applied, light launched from weakly coupled into waveguide, thus, one has high transmission at through port ADC. On other hand, when carrier density in changed, introduces some modification to refractive index film. As result, strongly cross-coupled low port. this Letter, ultra-compact 3.5- ?m-long experiments, fabricated well exhibits modulation bandwidth >40 GHz for first time.