Photorefractive beam coupling between orthogonally polarized light beams by linear dichroism in Cu-doped potassium sodium strontium barium niobate

Two-beam coupling between orthogonally polarized waves is demonstrated by u se of linear dichroism in Cu-doped potassium sodium strontium barium niobat e. A maximum coupling gain coefficient of approximately 4 cm-l is obtained at a grating spacing of 1 mu m and a wavelength of 514.5 nm, where linear d ichroism is moderate. The experimental results are compared with a theoreti cal model that allows a photorefractive grating to have an arbitrary phase shift with respect to an intensity-interference pattern. Fitting results in dicate that the grating is not 90 degrees-phase-shifted under open-circuit conditions. The contribution of the bulk photovoltaic field to the photoref ractive phase shift is discussed. (C) 1999 Optical Society of America [S074 0-3224(99)01201-1] OCIS codes: 190.0190, 190.5330, 190.7070.