Grating-coupled silicon-on-sapphire integrated slot waveguides operating at mid-infrared wavelengths

We demonstrate subwavelength bidirectional grating (SWG) coupled slot waveguide fabricated in silicon-on-sapphire for transverse electric polarized wave operation at 3.4 mu m wavelength. Coupling efficiency of 29% for SWG coupler is experimentally achieved. Propagation loss of 11 dB/cm has been experimentally obtained for slot waveguides. Two-step taper mode converters with an insertion loss of 0.13 dB are used to gradually convert the strip waveguide mode into slot waveguide mode. (C) 2014 Optical Society of America