Mechanisms for optical loss in SOI waveguides for mid-infrared wavelengths around 2μm

We report the measurement of optical loss in submicron silicon-on-insulator waveguides at a wavelength of 2.02 mu m for the fundamental TE mode. Devices were fabricated at IMEC and at A star STAR's Institute of Microelectronics (IME) and thus these measurements are applicable to studies which require fabrication using standard foundry technology. Propagation loss for strip and rib waveguides of 3.3 +/- 0.5 and 1.9 +/- 0.2 dB cm(-1) were measured. Waveguide bending loss in strip and rib waveguides was measured to be 0.36 and 0.68 dB per 90 degrees bend for a radius of 3 mu m. Doped waveguide loss in rib waveguides was measured for both n-type and p-type species at two doping densities for each doping type. Measured results from propagation, bending, and free-carrier loss were found to be in good agreement with analytical or numerical models. Loss due to lattice defects introduced by ion-implantation is found to be underestimated by a previously proposed empirical model. The thermal annealing of the lattice defects is consistent with removal of the silicon divacancy.