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

We demonstrate an ultra-thin silicon waveguide for wavelengths around 1.55 mu m, and mode converters designed for transitions to and from standard 500 nm x 220 nm strip waveguides. The devices were fabricated in a CMOS-compatible process requiring two photolithography and etch steps. The ultrathin waveguides exhibited losses of 2.01 +/- 0.231 dB/cm, exhibited bend radii as small as 30 mu m with losses of 0.05 +/- 0.005 dB per bend, and exhibited coupling losses of 0.66 +/- 0.014 dB to standard strip waveguides. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768296]