电子束辐射GeS_2-Ga_2S_3-CdS硫系玻璃的二次谐波发生效应

SECOND HARMONIC GENERATION OF THE GeS_2-Ga_2S_3-CdS GLASS IRRADIATED BY ELECTRON BEAM

用熔融-急冷法制备了在可见光区有较高透过率的GeS2-Ga2S3-CdS硫系玻璃,在电子束辐射的玻璃样品中观察到明显二次谐波发生效应,得到了对称性良好的Maker条纹。研究结果表明:当激光入射角在±(40°～50°)左右时,二阶非线性光学效应的相对强度出现最大值。通过表面化学蚀刻法进行了极化机理分析,发现在电子束辐射下,玻璃表面很薄的一层区域内形成局域直流强电场,破坏了玻璃的宏观各向同性,极化区域厚度大于理论计算结果。

Chalcogenide glasses of the GeS2-Ga2S3-CdS system with high transmittance in the visible region were obtained by the melt-quenching method. A prominent second harmonic generation （SHG） was observed from glasses after irradiation by an electron beam, and a Maker-fringe with good symmetry was also gained. The results show that the maximum of relative SHG intensities appears at an incidence angle of laser around ＋（40 °-50 °）. The SHG intensities have a close relationship with the irradiation conditions. The mechanism of polarization was analyzed through the surface chemical etching technique. Under the irradiation of electron beam, a local strong direct current electronic field is formed in a zone of the thin layer of the glass surface, which destroys the macroscopic isotropy of the glass. The thickness of the polarization zone is more than the theoretical calculations results.