Enhancement of blue photorefractive properties in Mg:Fe:Cu:SLiNbO3 crystals with near stoichiometry

Abstract

Using the top seeded solution growth technique, near stoichiometric Mg : Fe : Cu : SLiNbO 3 crystals have been grown by using K 2 O as flux. Infrared transmission spectra were measured and defect structure and change of threshold value were investigated. Using Kr + laser as light source (blue light with wavelength of 476 nm) the photorefractive properties of crystals were measured. The diffraction efficiency of 76.3%, the short response time of 11 s, the dynamic range of 27.39, the sensitivity of 2.09 cm/J, and the refractive index change of 8.67 × 10-5 were obtained. The blue photorefractive properties were enhanced. As the holes are the dominant charge carriers, the short wavelength blue light which exhibits high energy can excite the holes from both of the shallow and the deep trap centers with the same phase. It was found that the so-called optical damage-resistant dopant such as Mg 2+ ions no longer functioned as the damage resistant at 476 nm wavelength, but turned to enhance the blue photorefractive characteristics.