Ultra-shallow ridge waveguide microring resonators for narrow band photonic RF filters in conventional silicon-on-insulator platforms

We investigate the use of an ultra-shallow partial etch to form silicon microring resonators with high Q in a 250nm thick SOI device layer, to enable narrowband filters for RF photonic signal processing in conventional silicon photonics platforms. We demonstrate compact ring resonators formed by waveguides with as shallow as 25nm deep etches in a 250nm device layer and show significant improvement in fabrication-limited intrinsic Q with reduced etch depth. We demonstrate rings with loss Q's as high as 700k at an etch depth of 45nm.