【作者】 何漩；

【导师】 刘启明；

【作者基本信息】 武汉理工大学 ， 材料学， 2010， 硕士

【摘要】 随着激光的发现及应用,人们越来越关注物质在强光辐照的下所产生光倍频、光参量振荡等非线性现象。这些现象在实际中得到广泛的应用,尤其在光电子器件中的运用使得非线性光学这门学科成为许多学者关注的热点。本文根据麦克斯韦方程及电磁波在界面上的边界条件,分析入射基频光穿过空气-样品界面、在非线性介质中产生倍频光,以及穿透样品-空气界面后三个步骤,得到经激光与二阶非线性介质作用后,得到倍频光与基频光大小及方向的关系,分析这两束光相位匹配的过程,采用MathCAD软件对波长为1064nm的基频光在二阶非线性介质中的传播进行Maker条纹模拟,得到二阶非线性介质中产生的波长为532nm的倍频光的模拟公式。采用Maker条纹测试法,利用波长为1064nm的基频光穿过围绕一转轴进行转动的石英晶体样品、电场／温度场极化后的硫系玻璃样品及微晶玻璃样品,根据样品光滑表面与基频光光束之间的夹角的改变,来获得532nm的倍频光的空间周期分布的对称干涉条纹。将所得到的Maker条纹分别与晶体、电场／温度场极化后的硫系玻璃及极性微晶玻璃样品的实际的测量结果相对比,可以得到所模拟的程序与倍频晶体的Maker测量结果相吻合,对于极化后的硫系玻璃及极性微晶玻璃样品,在一定范围内模拟结果与测量结果相一致。本文对所得到的模拟计算方法进行理论分析,可以得到实验过程中偏振光的方向及样品结构的对称性等对其二次谐波的大小及方向的影响。从而对样品制备、Maker条纹测试的实际操作过程及二阶非线性极化机理有一定的指导意义。更多还原

【Abstract】 With the discovery and application of laser, the optical nonlinear phenomenon which was induced by irradiation of lasers in the materials, such as optical second-harmonic generation, and optical parametric oscillator so on, has been applied widely especially in photonic devices. These developments of applications make the nonlinear optics become the focus of investigation of researchers.In this paper, we analyzed three steps according to the Maxwell equations and boundary conditions, the transmission of fundamental wave from air to nonlinear medium, the second harmonic generation in the nonlinear medium and the transmission of fundamental and double frequency wave from nonlinear medium to air. According to the analysis of these three steps, the relations of amplitudes and directions between fundamental wave and double frequency wave were obtained to investigate the process of phase matching. The software MathCAD was performed to simulate the process of phase matching to obtain the intensity formula of double frequency wave generated in the nonlinear medium.When the fundamental wave transmitted the quartz, chalcogenide glasses poled by electrical/thermal fields or crystallized glasses which were rotated on one axe, the angles between the sample surface and fundamental wave would be varied. Due to this variation, the periodical interference fringes were spatially obtained. Comparing with the simulated results of Maker fringes and those three kinds of samples, we analyzed theoretically the simulation method in this paper and the adaptability of this method to different second nonlinear materials. For quartz, the simulated results were suitable to experience results. However, these simulated results were also suitable to those experience results to some extent. In this paper, the influence of polarized direction and samples’symmetry on the intensity and direction of second harmonic generation (SHG) has been obtained. These consequences were directive significance to fabrication of samples, experience of Make fringe measurement and understand of second-order nonlinear mechanism更多还原