Study on the third and second-order nonlinear optical properties of GeS₂-Ga₂S<suv>3</suv>-AgCl chalcohalide glasses

Third-order optical nonlinearities, chi((3)) of GeS(2)-Ga(2)S(3)-AgCl chalcohalide glasses have been studied systematically utilizing the femtosecond time-resolved optical Kerr effect (OKE) technique at 820nm, showing that the value of chi((3)) enhances with increasing atomic ratio of (S+Cl/2)/(Ge+Ga). From the compositional dependence of glass structure by Raman spectra, a strong dependence of chi;(3) upon glass structure has been found, i.e. compared with [Cl(x)S(3-x)Ge(Ga)-Ge(Ga)S(3-x)Cl(x)] ethane-like s.u. as the structural defectiveness, [Ge(Ga)S(4-x)Cl(x)] mixed tetrahedra make greater contribution to the enhancement of chi((3)). The maximum chi<sp>(3)</sp> among the present glasses is as large as 5.26x10(-13)esu (A1 (80GeS(2)-10Ga(2)S(3-) 10AgCl)), and the nonlinear refractive index (n2) of A1 glass is also up to 4.60x10(-15) cm(2)/W. In addition, using Maker fringe technique, SHG was observed in the representative A1 glass poled by electron beam (25 kV, 25 nA, 15 min), and the second-order optical nonlinear susceptibility is estimated to be greater than 6.1 pm/V. There was no evident structural change detected in the as-prepared and after irradiated A1 glass by the Raman spectra, and maybe only electronic transition and distortion of electron cloud occurred in the glasses. The large third/second-order optical nonlinearities have made these GeS(2)-Ga(2)S(3)-AgCl chalcohalide glasses as promising materials applied in photoelectric fields.