Determination of wavelength dependence of the effective charge carrier density of photorefractive crystals

초록

We propose and demonstrate a new method to determine accurately the wavelength dependence of effective charge carrier density of photorefractive crystals. A Ce-doped BaTiO<inf>3</inf> crystal was used in the experiments of demonstration. First, by writing a grating with two coherent beams at a fixed wavelength and measuring its diffraction efficiency for a weak tunable probing beam, the dispersion of effective electro-optic coefficient of the crystal was determined. Then by measuring the two-beam coupling coefficient at different wavelengths, we can determine accurately the variation with wavelength of the effective charge carrier density of the crystal.