Grating structures with phase mask period in silica-on-silicon planar waveguides

摘要

The resultant properties of a damage grating generated under phase mask processing conditions were investigated on a germanosilicate planar waveguide bilayer fabricated by plasma enhanced chemical vapor deposition. Direct writing in the waveguide silica-on-silicon material with a phase mask designed to produce 1550 nm Bragg gratings resulted in a damage grating with a period around 1 µm phase mask period. This does not agree with the expected period of around 0.5 µm for a first order diffraction grating satisfying the Bragg condition when the phase mask zero order is less than a few percent of the input beam.