非线性光学晶体CsLiB₆O₁₀用于光参量振荡器的线宽研究

【作者】 宋春荣；

【导师】 王丽；

【作者基本信息】 河北师范大学 ， 凝聚态物理， 2003， 硕士

【摘要】 论文对新型非线性光学晶体CsLiB₆O₁₀（CLBO）用于光参量振荡器（OPO）的输出线宽特性进行了理论研究。OPO是一种具有广泛应用前景的全固化相干辐射光源，而且具有宽的调谐范围、高的输出功率、高的转换效率等特点，使OPO的应用和开发具有重要的理论和实用价值，但是OPO的发展需要有高的光学特性和高的抗损伤阈值的晶体。对于很多应用，例如高分辨率的光谱研究，又需要OPO输出线宽较窄。近年研制的CLBO晶体具有有效非线性系数大、走离角小、允许范围宽等特点。论文对CLBO晶体的输出参量光的线宽特性进行了理论分析和模拟计算。基于自由运转的OPO不能提供所需的窄带线宽，理论上实现了利用棱镜、光栅、标准具等腔内元件压窄CLBO—OPO的线宽。 第一章介绍了光参量激光器及相关非线性晶体的发展状况，综述了CLBO晶体和OPO线宽的研究背景及其研究进展情况；第二章以355nm作为泵浦光，对影响CLBO晶体光参量振荡器线宽的各种物理机制进行了数值模拟计算、分析。根据能量动量守恒关系和CLBO的色散方程，详细分析了由于泵浦光的线宽、泵浦光偏轴泵浦、泵浦光的发散角、泵浦光功率超过参量光振荡阈值一定倍数、高增益系数、有效腔长波动以及自发辐射引起的参量光线宽，并得到了与BBO晶体在Ⅰ类、Ⅱ类相位匹配下比较的理论曲线。结果表明，泵浦光的发散角、泵浦光的偏轴泵浦、自发辐射对参量光的线宽影响较大。在远离简并点处，线宽较小，在简并点处，线宽较大。得到了CLBO—OPO的线宽要大于同等条件下BBO—OPO线宽的结论。第三章根据CLBO-OPO输出线宽较大的特点，理论上分析采用棱镜、光栅、标准具等线宽压窄元件来压窄输出参量光线宽，分别获得了小于Ztun、0.snm、0.06nm的输出线宽。更多还原

【Abstract】 We have carried out thoroughly theoretical the linewidth characteristic of the optical parametric oscillator (OPO) by the use of a kind of new nonlinear optical crystal- CsLiB6O10(CLBO). OPO is one of the most promising all solid state source of coherent radiation that is tunable over a broad wavelength range and high average power output with a high conversion efficiency. The application and exploitation of it has important value of not only in theory but also practicality. But the development of OPO requires the high optical quality and high damage threshold crystals. For many applications, for example, high-resolution spectroscopic studies, however, the narrow linewidth is necessary. The CLBO crystal, which has been discovered in recent years, the efficiency nonlinear coefficient is larger ,walk-off angle is smaller and permitted parametric is wider than that of BBO. We have studied and simulated the theory of linewidth of parametric light. A free-running OPO does not provide the required narrow-band radiation; however, the bandwidth can be reduced considerably by use of intracavity elements such as prisms and gratings or by etalons with a narrow-band laser on either the signal or the idler wavelength.In the sectionl, we introduced the development of OPO and the correlative nonlinear optical (NLO) crystal, summarized the background and the recent advance of the CLBO and linewidth of OPO; In the section2, we have studied and stimulated linewidth of parametric light of CLBO optical parametric oscillators pumped by 355nm by computer. We presents a detailedstudied of the linewidth of parametric light in CLBO-OPO caused by the linewidth of pumping beam, off axis phase matching, divergence angle of pumping, time above threshold, high gain coefficient of NLO crystal, fluctuate of cavitylength, spontaneous radiation, according to the momentum and energy conversion laws, and the Sellmeier equations of the CLBO, We calculated curves of the type -I and type -II compared with the BBO’s. It is shown that the divergence angle of pumping beam and off axis pumping and spontaneous radiation influenced the linewidth of parametric light more quickly than those of other factors did , and the linewidth of parametric light is very narrow far away from the degeneracy point ,and the linewidth begins to large quickly at the degeneracy point. We got the conclusion that the linewidth of CLBO is higher than that of BBO at the same condition. In sections, we reduced the linewidth of parametric light considerably by use of the elements such as prisms and gratings or by etalons. We can obtain the linewidth less 2nm, less O.Snm, less 0.06nm, respectively.更多还原