Photoinduced nonlinear optical phenomena in Sb2Se3-BaCl2-SnCl2 glasses

Abstract

Photoinduced nonlinear optical phenomena have been studied in amorphous Sb₂Te₃-CaCl₂-SnCl₂ glasses using photoinduced optical second harmonic generation (SHG). The photoinduced SHG signal was measured for double frequency of a CO₂ laser (λ = 5.3 μm) using a photoinducing CO laser (λ = 5.5 μm). We have found that the SHG signal intensity increases with increase of the CO laser photoinducing exposure and achieves its maximum value after 1.5 h. Absolute values of the SHG signals were more than one order in magnitude smaller comparing to a χ₂₂₂ tensor component for the ZnSe single crystals. The SHG signal strongly increases if temperature decreases from 39 to 16 K. Femtosecond probe-pump measurements indicate existence of the SHG maximum at pump-probe time delay of about 43 ps. It is suggested that Sb-Se tetrahedra play a key role in the observed photoinduced nonlinear optical effects. Degree of noncentrosymmetry of corresponding bonds depends on time of the CO-laser illumination, temperature and mechanical stresses. Simultaneously, the investigated glasses can serve as promising materials for a femtosecond IR quantum electronics.