Cubic Nonlinearity of Tellurite and Chalcogenide Glasses: Terahertz-Field-Induced Second Harmonic Generation vs. Optical Kerr Effect

Abstract

Third-order nonlinear susceptibilities χ3−2ω;ω,ω,0 and χ3−ω;ω,−ω,ω responsible for electric-field-induced second harmonic generation and the optical Kerr effect were measured and directly compared for tellurite and chalcogenide glasses. The nonlinear coefficients were found by measuring the second harmonic radiation from samples under the action of an external field of terahertz pulses and by the classical z-scan technique, respectively. The influence of ambient air and helium gas on second harmonic generation was analyzed. It was demonstrated that both susceptibilities χ3−2ω;ω,ω,0 and χ3−ω;ω,−ω,ω have close absolute values, which shows the dominant role of nonresonant electronic nonlinearity in the studied glasses.