【作者】 路洋；

【导师】 姚建铨；

【作者基本信息】 天津大学 ， 物理电子学， 2004， 硕士

【摘要】 本文主要在周期极化晶体准相位匹配技术的非线性频率变换方面展开了一些初步的研究和分析。第一章在对准相位匹配技术的基本理论,特点和未来前景以及周期极化晶体的特性,制作和分类做了必要的介绍以后,第二章对THz辐射的产生方法进行了综述,对其各种常用的探测手段进行了比较。特别分析和总结了差频产生THz波的方法,并详细介绍了THz辐射的特性,对其研究现状进行了分析。在第三章中提出我们自己的研究方法和具体的项目实施方案。多年来,科学界对THz波段的各种特性知之甚少,主要是由于没有切实可行的THz波产生方法和检测手段,以至于该波段被称为电磁波谱中的THz空隙,可以说是电磁波谱研究的空白,也是电磁波谱中有待进行全面深入研究的最后一个频率段。本文第四章对宽带光源的发展进行了综述,列举了宽带光源的种类,分析了其优缺点及适用范围。在此基础上对基于准相位匹配的新型宽带光源进行了介绍;探讨了准相位匹配参量过程实现宽带光源的原理;对QPM-OPG的泵浦波长的选择和极化周期的确定进行了数值计算;对参量振荡器的泵浦源946nm激光器进行了理论实验研究,并对未来做了展望。最后,本文第五章对准相位匹配二次谐波产生进行了综述,并进行了理论分析和基于PP-MgO:SLT的外腔倍频实验研究。本文的创新点如下:1.直接利用增益介质(如Nd: YAG)的发射截面相近的谱线作为泵浦光和信号光,注入到PPLN中,获得THz的准相位匹配差频输出;2.利用两个波长接近的信号光在倾斜周期PPLN中实现差频,产生THz波,通过对光学参量振荡PPLN晶体的温度和角度调谐,实现双波长信号光的可调谐运转,从而获得宽调谐范围的THz波输出;3.实验上进行了LD端面泵浦的946nmNd:YAG激光器的研制,获得最大功率为3.05W,斜效率为24%的连续输出,并以此为PPLN-OPG泵浦源的实验研究基础;4.实验上,我们获得平均输出功率为1.8W,重复频率为50kHz的准连续946nm激光输出。同时进行了946nm准连续激光倍频的相关实验。在基频光入射平均功率为525mW时,获得473nm激光最高平均输出功率为79.5mW,倍更多还原

【Abstract】 In this thesis we introduce quasi-phase-matching theory, characters and prospectfirstly. In chapter 2 of this paper, we present a brief overview of development ofTHz-wave technology on generations, detections, measurements and applications. Inthe next chapter, we focus on the THz-wave generation by nonlinear differencefrequency mixing. Two designs of THz generation are demonstrated.A new-style broadband light source was theoretically analyzed and its pump source,946nm Nd: YAG quasi-three-level laser, was investigated roundly and thoroughly inchapter 4. In the last part of the paper we demonstrated a continuous wave single-passextra-cavity frequency doubling by use of MgO doped stoichiometric lithium tantalite(PP-MgO: SLT). The maximum output of the second harmonic green light is 905mWwith the pumping power of 7.69W. The second harmonic conversion efficiency is11.77%.There following innovation points:1. We used nonlinear difference frequency generation in PPLN that directly utilizedall-solid-state laser such as Nd: YAG laser as the pumping source and signal togenerate THz radiation.2. To obtain THz generation we used an optical parametric oscillator with twoPPLN crystals in the same cavity to generate two signals as the source of DFG.3. We studied on diode-laser-end-pumped 946nm Nd: YAG laser in the operation ofcw and qcw then used the laser as the pumping source of PPLN-OPG. Also weobtained the SHG of 946nm laser.4. We realized dual-wavelength continuous wave laser operation at 1064nm and 946nm in Nd: YAG.5. We demonstrated a continuous wave single-pass extra-cavity frequency doublingby use of MgO doped stoichiometric lithium tantalite (PP-MgO: SLT).更多还原