PHOTOREFRACTIVE AND OPTICAL-PROPERTIES OF CERIUM-DOPED (SRCA)2NANB5O15

The photorefractive effect is demonstrated in a single crystal of ferr oelectric Ba-modified Ce-doped (SrCa)2NaNb5O15, for the first time to our knowledge. From two-beam coupling the gain and the time response w ere found. The maximum intensity gain with ordinary light at a 488-nm wavelength was GAMMA - 10 cm-1, while the photorefractive time respons e was determined to be 1.85 s at an incident intensity of I = 1 W/cm2. The phase shift of the index gratings from the intensity grating was found to vary with angle from approximately 28-degrees at a 79-degrees crossing angle to 55-degrees at a 13-degrees crossing angle. The dark decay was measured, and the two-beam coupling intensity gain was foun d to oscillate with time. The oscillation period and the dc component were found to depend on the crossing angle. Beam fanning was observed with a transmitted beam reduction of 1.61 optical density and a time r esponse of tau approximately 5.6 s at I = 230 mW/cm2. Finally, anisotr opic conical diffraction was observed in the form of a partial ring pa ttern about the transmitted (extraordinary-polarized) incident beam in a direction opposite the beam fan. When the dependence of the angle b etween the ring and the transmitted beam is fitted to the change in th e incident angle, it is possible to measure the birefringence, which w as n(e) - n(o) = -0.051.