MEASUREMENT OF PHOTOREFRACTIVE COUPLING-CONSTANT OF BATIO3 USING THE VARYING INTERACTION LENGTH METHOD

The intrinsic problems, such as beam fanning and internal beam reflect ion, in measuring the photorefractive coupling constant are discussed. We propose a new technique, the varying interaction length method, to avoid them. In this method, the coupling constant is obtained by diff erentiating the coupling strength that is measured with changing the i nteraction length. We applied this method to BaTiO3 and obtained a 10- 20% larger coupling constant compared with that of the conventional me thod.