Silicon waveguides and devices for the mid-infrared

We report on the design, fabrication, and characterization of silicon-on-insulator rib and strip waveguides at wavelengths longer than 3.7 mu m. Propagation losses of 1.5 +/- 0.2 dB/cm at 3.73 mu m and 1.8 +/- 0.2 dB/cm at 3.8 mu m have been measured for rib waveguides, whilst submicron strip waveguides exhibited propagation losses of 4.6 +/- 1.1 dB/cm at the wavelength of 3.74 mu m. A 1 x 2 multimode interference (MMI) splitter and racetrack resonators based on submicron strip waveguides are also examined. Optical losses of 3.6 +/- 0.2 dB/MMI and a racetrack resonator Q-value of 8.2 k are obtained at 3.74 mu m. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4753948]