Non-photorefractive LiNbO₃:Mg as the effective material for the nonlinear optics

Abstract

The comparative study of optical properties of Mg-doped and Mg-nondoped LiNbO₃ and Fe-doped LiNbO3 crystals was carried out. In all the crystals doped with Mg ≥ 1 wt.% the value of photorefraction decreases not less than by 102 in spite of Fe incorporation up to 0.1 wt%. At room temperature the nonlinear optical elements of LiNbO₃:2.4 wt% Mg reveal the conversion efficiency of SHG more than 25% with phase matching angle of 90[ddot]. X-ray and UV-induced changes of the optical absorption spectra reveal the alteration of the electron acceptor type in Mg-doped crystals. On the contrary to pure LiNbO₃, in LiNbO3 doped by Mg the Fe³⁺-ion is not more the electron acceptor center, what is followed by the change of the photoelectric and consequently photorefractive properties. Mg incorporation affects the ESR spectrum of Fe₃₊ in LiNbO₃ as well.

Key Words:

• photorefraction
• photogalvanic
• optical damage
• electrooptic