RAMAN MICROPROBE CHARACTERIZATION OF PHOTOREFRACTIVE NONLINEARITY IN TI-LINBO3 CHANNEL WAVE-GUIDES

We report on the use of a Raman microprobe to investigate the nonlinear optical process of polarization in Ti:LiNbO3 optical channel waveguides. Selection rules allow the Raman scattered signal collected in a direction orthogonal to the plane of the waveguide to provide information regarding the polarization state of the light propagating in the waveguide. From this data a threshold value of power necessary to initiate the polarization rotation is obtained and used to calculate a value of beta-15, an asymmetric component of the photovoltaic tensor. The value of beta-15 for an X-cut, Y-propagating channel waveguide was found to be 8X10(-13) A/W and that for a rapid thermally annealed Z-cut, Y-propagating sample 4x10(-14) A/W.