Ultra-thin silicon-on-insulator strip waveguides and mode couplers

Abstract

We demonstrate an ultra-thin silicon waveguide for wavelengths around 1.55 μm, and mode converters designed for transitions to and from standard 500 nm × 220 nm strip waveguides. The devices were fabricated in a CMOS-compatible process requiring two photolithography and etch steps. The ultra-thin waveguides exhibited losses of 2.01 ± 0.231 dB/cm, exhibited bend radii as small as 30 μm with losses of 0.05 ± 0.005 dB per bend, and exhibited coupling losses of 0.66 ± 0.014 dB to standard strip waveguides.