Influence of doping on OH absorption in LiNbO₃ crystals

Abstract

Abstract Undoped, Cr doped and Mg, Cr codoped LiNbO 3 crystals were grown by conventional Czochralski technique. Comparative study was carried out using Fourier transform infrared (FTIR) and UV‐Visible spectroscopy. Infrared optical absorption for OH – ion has been used to study the effect of dopants on the crystals. The peak position of OH – shift to 3535 cm ‐1 for Mg, Cr codoped crystals compared to 3484 cm ‐1 for undoped and Cr doped crystals. Prominent absorption bands are found in the visible region centered at 480 nm (20833 cm ‐1 ) and 653 nm (15313 cm ‐1 ) in Cr doped crystals. Whereas in Mg, Cr codoped crystals these broad absorption bands are red shifted to 517 nm (19342 cm ‐1 ) and 678 nm (14749 cm ‐1 ). UV cutoff in Cr doped crystals shift towards higher wavelength compared to undoped LiNbO 3 crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)