Asymmetric dual GeSi/Si Bragg mirror and photodetector operating at 632 and 780 nm

Abstract

We report the successful combination of asymmetric and dual mirror designs to fabricate a strained-layer GeSi/Si Bragg mirror with twin peaks at 632 and 780 nm. The absorption in the GeSi/Si mirror is found to be small and is compensated by the increased refractive index step available at shorter wavelengths. We also propose a dual photodetector that will exhibit high efficiencies at both the resonant wavelengths. The small absorption thickness of this photodetector as compared to conventional silicon photodiodes is expected to result in higher speeds.