Wavelength dependent propagation loss characteristics of SiGe/Si planar waveguides

The propagation loss of Si_0.9Ge_0.1/Si planar optical waveguides has been measured at wavelengths of 1.15 and 1.523 mu m. The results show that these waveguides have a low propagation loss (<1 dB/cm) at a wavelength of 1.523 mu m, which is due to the intrinsic absorption of SiGe whereas at a wavelength of 1.15 mu m its loss is determined by both the SiGe absorption edge and defects at the SiGe/Si interface.