Growth and optical homogeneity investigations of Fe and Fe:Mn codoped LiNbO₃ crystals

Abstract

Lithium niobate (LiNbO 3 ) crystals doped with Fe and Fe:Mn were grown by Czochralski technique. The doping concentrations of Fe and Mn were optimized. Transmission studies reveal broad absorption band centered at 488 nm. The UV cutoff observed for Fe doped LiNbO 3 is 358 nm whereas for Fe:Mn codoped LiNbO 3 is 352 nm. This decrease in UV cutoff for Fe and Mn codoped LiNbO 3 compared to only Fe doped LiNbO 3 is due to the increase in Li/Nb ratio. Optical homogeneity was assessed using conoscopy and birefringence interferometry. Dark and photo conductivity measurements prove that LiNbO 3 is a negative photo conducting material.