Experimental demonstration of propagation characteristics of mid-infrared photonic crystal waveguides in silicon-on-sapphire

We provide the first experimental demonstration of optical transmission characteristics of a W1 photonic crystal waveguide in silicon on sapphire at mid infrared wavelength of 3.43 μm. Devices are studied as a function of lattice constant to tune the photonic stop band across the single wavelength of the source laser. The shift in the transmission profile as a function of temperature and refractive index is experimentally demonstrated and compared with simulations. In addition to zero transmission in the stop gap, propagation losses less than 20 dB/cm are observed for group indices greater than 20 below the light line while more than 300 dB/cm propagation losses are observed above the light line, characteristic of the waveguiding behavior of photonic crystal line defect modes.