Optical Properties of Crystals of Lithium Niobate–Tantalate Solid Solutions LiNbTaxO3.

The growth system has been upgraded, technological growth parameters have been optimized, and a high-quality crystal has been grown from the LiNb_0.95Ta_0.05O₃ charge. Spectral dependences of the transmittance of a sample cut from this crystal have been measured before and after the transition to the single-domain state in the range of 300–700 nm with allowance for anisotropy and dichroism. Spectral dependences of the absorption coefficient α(λ) and degree of dichroism Δ(λ) have been obtained. The dependences α(λ) contain an absorption band at λ ~ 480 nm, regardless of the light propagation direction. When light propagates perpendicular to the optical axis, absorption bands at λ ~ 560, 608, 620, and 656 nm can additionally be observed. The transition to the single-domain state leads to sample bleaching. The dependences Δ(λ) for the X and Y cuts are characterized by identical extrema, whose positions correspond to the absorption bands in the dependences α(λ); additional extrema manifest themselves at λ ~ 400 and 445 nm. When light propagates along the optical axis, the dependences Δ(λ) are nonzero; they are characterized by much smaller values (in comparison with the directions perpendicular to the optical axis) and have extrema at λ ~ 440, 560, 600, 620, and 640 nm. [ABSTRACT FROM AUTHOR]