SINGLE POLARIZATION OPTICAL WAVE-GUIDE ON SILICON

A single polarization optical waveguide structure is introduced demonstrated experimentally. The optical waveguide structure considered is a silicon nitride film deposited onto an oxidized silicon wafer so as to form a single-mode planar waveguide. Single polarization is achieved by choosing layer thicknesses so that the attenuation due to substrate coupling for the TM mode is much larger than that for the TE mode. Calculations are presented to define ranges of design parameters over which TM attenuation can be 3-4 orders of magnitude higher than that for TE. In one sample having a TE loss of 0.28 dB/cm measured at a wavelength of 0.63-mu-m a ratio of TM to TE attenuation of over 750 is experimentally demonstrated.