Transparent amorphous silicon channel waveguides and high-Q resonators using a damascene process.

We demonstrate a damascene process for fabricating amorphous silicon (a-Si), single-mode optical channel waveguides and high-Q racetrack resonators. This process is compatible with thermal budget limitations for a-Si phase stability. It offers improved optical transmission and facilitates hydrogen encapsulation for process integration of a-Si waveguide cores. At 1,550 nm, the average measured transmission loss coefficient is 2.5+/-0.1 dB/cm for the TE mode, comparable with high-quality single crystalline silicon counterparts. The racetrack resonators have mid-10(4) to 10(5) quality factors (Q) and extinction ratios as high as 25 dB.