Efficient hologram recording in LiNbO3 : Fe using optical pulses

Abstract
A Q‐switched frequency‐doubled Nd : YAG laser was used to record holograms in LiNbO3 : Fe. For 1% diffraction efficiency, only 50 mJ/cm2 was needed, as compared to 500 mJ/cm2 for cw recording. Induced absorption, comparable in magnitude with the linear absorption at 647 nm, was observed during hologram recording. This indicates the existence of secondary absorption centers in LiNbO3 : Fe. Their contribution to the enhanced photorefractive effect is discussed.