Nonlinear optical properties of congruent and Li-compensated LiNbO3 crystals

We carried out a comparative study of the optical properties of congruent a nd lithium-compensated LiNbO3 crystals. The vapor transport equilibration(V TE) method was applied to a thin congruent crystal to obtain the latter sam ple. Among several signatures of Li-compensation in the bulk material, we o bserved changes in the UV absorption edge and the Raman linewidth of the A( 1)(z) mode. Nonlinear optical properties such as second harmonic generation (SHG) and photorefractivity have been comparatively studied. The SHG phase matching wavelength had a significant shift after VTE. A tunable SHG exper iment proved to be a sensitive method for probing a small change in the Li- composition.