LOSSES IN POLYCRYSTALLINE SILICON WAVE-GUIDES

The losses of polycrystalline silicon (polySi) waveguides clad by SiO2 are measured by the cutback technique. We report losses of 34 dB/cm a t a wavelength of 1.55 mu m in waveguides fabricated from chemical mec hanical polished polySi deposited at 625 degrees C. These losses are t wo orders of magnitude lower than reported absorption measurements for polySi. Waveguides fabricated from unpolished polySi deposited at 625 degrees C exhibit losses of 77 dB/cm. We find good agreement between calculated and measured losses due to surface scattering. (C) 1996 Ame rican Institute of Physics.