GeS_2-Ga_2S_3-CsCl玻璃的三阶非线性光学性能研究

Study on third-order optical nonlinearity of GeS_2-Ga_2S_3-CsCl chalcohalide glasses

用传统的熔融急冷法制备了组分为(100-2x)GeS_2-xGa_2S_3-xCsCl(x=15,20,25 mol%)系列硫卤玻璃,测试了样品玻璃的吸收光谱.采用Z-扫描方法测试了样品的三阶非线性光学特性.分析了激光光子能量与玻璃三阶非线性光学特性的关系,并研究了组分变化对玻璃的三阶非线性性能的影响.研究结果表明,光子能量的少许改变可以使非线性吸收系数在一个较大的范围内变化,随着光子能量的增大,玻璃的非线性吸收系数β增大;当光子能量趋近于0.5E_g时,β值趋近于0,玻璃有最佳的品质因子;玻璃样品中CsCl含量的增加使得玻璃的光学带隙E_g增大,短波截止边蓝移,非线性吸收系数β减小.但是由于结构与带隙对光学非线性的影响相反,非线性折射率γ值变化不大.该结果表明样品的光学非线性性能由光学带隙和结构两方面因素共同决定,对今后研究全光开关用硫系玻璃具有一定的指导意义和参考价值.

Abstract Chalcohalide glasses with compositions of （100-2χ） GeS2-χGa2S3-χCsCl （χ = 15, 20, 25） are synthesized by the conventional melt-quenching method. Third-order optical nonlinearities of these glasses are studied using the Z-scan technique. The relationship between photon energy and optical nonlinearity is analyzed. Moreover, the effect of glass composition on the third-order nonlinearity is investigated. The results show that just a small variation of the excitation photon energy causes the β value of samples to change in a large range. The 13 value increases with the enhancement of excitation photon energy. When the photon energy is close to 0.5 Eg, the β value is close to 0 and the factor of quality of the glass reaches an optimal value. The increase of CsCl content enlarges the optical band gap Eg, which leads to the blue-shift toward the short edged wavelength, and lowers the β value. However, the γ value varies little because of the opposite effect on the optical nonlinearity between the structure and the band gap Eg. In this work, the optical nonlinearity is shown to be dependent on band gap and structure, and the results have a certain directive significance and reference value for future research.