Ge waveguide photodetectors with responsivity roll-off beyond 1620 nm using localized stressor

We report a novel Ge waveguide photodetector and the fabrication on silicon-on-insulator (SOI) platform. Localized stressor structures were incorporated to tune the responsivity roll-off wavelength. With the localized stressor structure, the roll-off in responsivity is found to be red-shifted from 1520 nm to beyond 1620 nm, i.e., a flat responsivity over the entire C- and L-band is obtained. This technique makes Ge a promising material for fabricating monolithic high-responsivity receivers covering the entire C- and L-band fiber optic communications.