8微米ZGP级联OPA实验研究

发布时间：2018-06-02 19:34

  本文选题：8微米 + OPO　； 参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：8-12μm长波红外波段位于大气窗口且对人眼安全,该波段光源在光电对抗、激光医疗、激光雷达和有毒气体探测等方面具有重要的应用价值。目前,8-12μm波段激光的主要获取手段是光学参量振荡和光学参量放大,利用非线性转换将低波长的激光向高波长转换。在常用的非线性频率转换晶体中,Zn Ge P2晶体凭借极高的有效非线性系数和良好的机械强度、高热导率等优点,成为获得8-10μm波段激光首选晶体。由于ZGP晶体光学性质的限制,泵浦光的波长需要在2μm以上,而且获得较高功率的8-10μm波段激光比较困难。本论文的目的是探索级联式OPA方法对8μm功率的放大效果以及这种方法是否具有应用价值。级联光学参量放大(OPA)技术是通过ZGP光学参量振荡(OPO)产生的2.8μm信号光对8μm闲频光进行OPA,根据泵浦光和种子光偏振方向,OPO和OPA中ZGP晶体的匹配方式只能为一类+二类或二类+一类,本文中采用的是前者。由于这种方法文献中没有人报道,所以我们开始需要验证级联OPA方法的可行性。我们利用脉冲能量较大的泵浦光验证方法的可行性,利用平均功率较高的泵浦光探索影响OPA放大效果的因素。为此,我们搭建了两套泵浦源系统,第一套通过最高输出重频1k Hz能量30m J的Ho:YAG激光器泵浦ZGP OPO,获得了1.23W的8μm和4.34W的2.8μm激光;第二套通过最高输出重频16k Hz平均功率110W的Ho:YAG激光器泵浦ZGP OPO,获得了平均功率3.05W的2.8μm和12.3W的8μm激光。光学参量放大是三波混频的一种,我们通过求解三波混频耦合方程组得到了OPA光学参量放大系数公式,放大系数和初始泵浦光光强以及ZGP晶体长度有关。在大能量OPA实验中,通过分光合束装置将泵浦光和种子光调节重合后,8μm功率由1.23W增益到1.41W,确定了级联OPA方法是可行的;在高功率OPA实验中,验证了光斑重合程度、光斑大小和泵浦光初始光强因素对OPA放大效果的影响。最后,通过对光学参量振荡器和分光合束装置结构进行优化,级联OPA将8μm平均功率由3.52W放大到4.7W,总放大倍数为1.34,考虑到分光合束装置带来的损耗,OPA放大倍数为1.42,具备了一定的应用价值。
[Abstract]:The 8-12 渭 m long wave infrared band is located in the atmospheric window and is safe to the human eye. The light source in this band has important application value in optoelectronic countermeasure, laser medical treatment, lidar and toxic gas detection and so on. At present, optical parametric oscillation and optical parametric amplification are the main methods of obtaining 8-12 渭 m wavelength laser. The low wavelength laser is converted to high wavelength by nonlinear conversion. In common nonlinear frequency conversion crystals, Zn-Ge-P2 crystal has become the preferred crystal for obtaining 8-10 渭 m laser due to its high effective nonlinear coefficient, good mechanical strength and high thermal conductivity. Due to the limitation of optical properties of ZGP crystal, the wavelength of pump light needs to be more than 2 渭 m, and it is difficult to obtain 8-10 渭 m wavelength laser with high power. The purpose of this thesis is to explore the amplification effect of cascade OPA method for 8 渭 m power and whether this method has application value. The cascade optical parametric amplification (OPA) technique is a 2.8 渭 m signal light generated by ZGP optical parametric oscillation. According to the polarization direction of pump light and seed light, the matching mode of ZGP crystals in OPA can only be a second or a second class. The former is used in this paper. Since this method has not been reported in the literature, we need to verify the feasibility of cascaded OPA method. We use the pump light with high pulse energy to verify the feasibility of the method, and use the pump light with higher average power to explore the factors that affect the amplification of OPA. For this reason, we have set up two pump source systems. The first one is pumped by the Ho:YAG laser with the highest output repetition frequency of 1kHz energy 30mJ, and the 1.23W 8 渭 m and 4.34W 2.8 渭 m laser are obtained. The second set is pumped by a Ho:YAG laser with a maximum output repetition rate of 16 kHz and an average power of 110 W. The average power of the ZGP laser is 2.8 渭 m and 12.3 W, respectively, and the average power is 2.8 渭 m and 12.3 W, respectively. Optical parametric amplification is a kind of three-wave mixing. By solving the coupling equations of three-wave mixing, we obtain the formula of OPA optical parametric magnification factor, which is related to the initial pump light intensity and the length of ZGP crystal. In the OPA experiment of large energy, it is determined that the cascade OPA method is feasible after the pump light and seed light are adjusted and coincident by a photosynthetic beam splitter from 1.23W to 1.41W, and the degree of spot coincidence is verified in the high-power OPA experiment. The effect of spot size and initial intensity of pump light on the amplification of OPA. Finally, by optimizing the structure of optical parametric oscillator and photosynthetic beam splitting device, The average power of 8 渭 m was amplified from 3.52 W to 4.7 W, and the total magnification was 1.34 by cascaded OPA.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN212

【参考文献】

中国期刊全文数据库 前1条

1 邹振宁,冷锋,周芸;光电对抗技术和装备现状评析[J];电光与控制;2004年03期

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