Optical limiting and speckle of low power continuous wave laser beams using nonlinear scattering in photorefractive Zr: LiNbO₃ crystals

Abstract

The optical limiting caused by nonlinear scattering in the photore-fractive Zr-doped LiNbO 3 crystals was studied for lower-power laser beams with wavelengths of 514.5 and 532 nm. The measurements of speckle evolution indicate that the samples with 0.625 [Zr] 1.25 mol% exhibit the very large gain factor for holographic amplifi-cation of noise gratings. Based on the direct measurements of the output power depending on the input one, we conclude that these samples behaved as hard optical limiters for the laser beams with a low incident power. Thus, these crystals find their potential applica-tion in the optical limiting devices.