Comparison of Raman Spectra of Optically Nonlinear LiTaO 3 :Cr 3+ (0.005 wt%) Crystal Laser Excited in Visible (532 nm) and Near-IR (785 nm) Areas.

Raman spectra have been excited by the radiation of lasers generatingon in the visible (532 nm) and near-IR (785 nm) ranges in a LiTaO₃:Cr³⁺ (0.005 wt%) crystal. The obtained spectra were compared. Recorded Raman spectra contained bands in the range of <900 cm⁻¹ (first order) up to 2000 cm⁻¹ (second order). The Raman spectra of the second order, excited by near-IR laser radiation, were located against the background of a wide, luminescent halo. The frequency of a single low-intensity band exceeded the exact frequency of an overtone corresponding to the completely symmetric fundamental 4A₁(z)LO mode. The attribution of other second-order bands with higher frequencies remains unclear. [ABSTRACT FROM AUTHOR]