【作者】 翁文乐；

【导师】 刘友文；

【作者基本信息】 南京航空航天大学 ， 光学工程， 2009， 硕士

【摘要】 本文主要是基于准相位匹配光学频率变换技术,利用二次谐波发生过程和光学参量振荡过程对非线性光学晶体掺镁近化学计量比钽酸锂晶体的折射率进行测量,拟合得到用于计算不同温度和频率光波在此晶体中的折射率公式——Sellmeier公式,并用数值模拟方法研究了准相位匹配结构参数以及通过电光效应调节二次谐波发生过程中所产生的级联非线性相移。本文主要内容如下:1.阐述了准相位匹配技术的概念,介绍了国内外研究历史、现状与热点,并着重介绍了周期极化晶体;2.从理论上研究了周期性极化介质中的耦合波方程,系统地阐述了准相位匹配技术的原理,并着重介绍了多个利用准相位匹配技术实现光学频率转换的应用过程;3.介绍了钽酸锂晶体的物理和光学特性,并介绍了对钽酸锂晶体折射率测量研究的国内外历史,并通过OPO和SHG实验对基于掺镁近化学计量比钽酸锂晶体的变频过程进行了测量,通过曲线拟合的方法得到了计算此晶体折射率的Sellmeier方程4.介绍了非线性相移产生的原理,并对QPM结构中的级联非线性相移对SHG转换效率的影响进行了分析,对通过设计各种参数调节非线性相移来提高SHG转换效率。同时利用数值模拟手段对通过电光效应调节级联非线性相移进行控制的过程作了研究,并介绍了非线性相移的各种应用。本文的研究意义:基于准相位匹配技术的非线性光学频率转换过程在如今受到了广泛的关注。本文研究的非线性晶体掺镁近化学计量比钽酸锂折射率测量方法以及所得结果,对基于此种晶体的光学应用提供了重要的参数。本文研究的级联非线性相移的控制调制对光学频率转换效率的优化以及利用非线性相移的各种光学器件的设计提供了很大的技术支持。更多还原

【Abstract】 The temperature-dependent refractive indices of near-stoichiometric LiTaO3 (SLT) doped with MgO, i.e., Sellmeier equation, were presented by means of the quasi-phase-matched (QPM) second-harmonic generation (SHG) and optical parametric oscillator (OPO) processes. The cascaded nonlinear phase shifts in the QPM structure were investigated by adjusting the structure parameters and applying the external field by means of the numerical analysis..The main contents of this dissertation are as follows:1. We introduce the quasi-phase matching technique concept and its advantages,describe the history and domestic and overseas development in this field. The periodically poled nonlinear optical crystals are emphasized;2. The coupled-wave equation in the periodically poled crystal is studied theoretically and the principles of QPM technology was elaborated systematically with emphasis on several wavelength conversion applications based on this technology;3. The physical and optical characteristics of LiTaO3 and the history of research on the refractive indices of this crystal were introduced. And then we conducted the SHG and OPO experiments based on the Mg-doped SLT and used the derived experimental data to obtain the Sellmeier equation of Mg-doped SLT with least-square curving fitting method;4. We theoretically introduced the nonlinear phase shifts, numerically analysis its effect on the efficiency of SHG process based on QPM technology and by designing different parameters we optimize the efficiency. Control of the nonlinear phase shifts by electro-optic effect was also studied by numerical simulating method and different applications of the nonlinear phase shifts were introduced.The significance of this dissertation: wavelength conversion process based on QPM technology has been attracting wide attention recently. The Sellmeier equation of MgO-doped SLT will be helpful optical applications based on this material because of the accurate parameters. And the study and analysis on the cascaded nonlinear phase shifts in QPM structure will provide support for the designing and application of optical devices based on QPM technology.更多还原