Abstract
A novel mechanism is used to record photorefractive gratings in dielectric crystals. The photon energy of near-ultraviolet recording beams is larger than the energy gap, and the absorbed photons excite electrons from the valence to the conduction band. These interband photorefractive gratings in undoped KNbO3 show a faster response than gratings recorded in the same material with visible light, i.e., below band-gap excitation. We measured a response time τ = 5 μs for an intensity I = 1 W/cm2 and a refractive-index change of 2 × 10−6. In a transversal readout geometry, large diffraction efficiencies of 60% in 7.5-mm-long crystals are demonstrated. Interband photorefractive gratings are only weakly affected by visible light.
© 1993 Optical Society of America
Full Article | PDF ArticleMore Like This
Philipp Dittrich, Bozena Koziarska-Glinka, Germano Montemezzani, Peter Günter, Shunji Takekawa, Kenji Kitamura, and Yasunori Furukawa
J. Opt. Soc. Am. B 21(3) 632-639 (2004)
I. Biaggio, M. Zgonik, and P. Günter
J. Opt. Soc. Am. B 9(8) 1480-1487 (1992)
G. Montemezzani, M. Zgonik, and P. Giinter
J. Opt. Soc. Am. B 10(2) 171-185 (1993)