2.79μm电光调Q超高斯光束泵浦的高效率中红外ZGP-OPO研究

Mid-infrared laser radiation has important applications in spectroscopy, bio-medicine, atmospheric detection, optoelectronic countermeasures and etc. To obtain efficient mid-infrared laser radiation, 2.79μm super-Gaussian beam with high beam quality and peak power is proposed to pump the ZGP-OPO, to solve the low conversion efficiency caused by the nonuniform distributed pump beam, backconversion and walk-off effect in the mid-infrared OPO. The Super-Gaussian mirror based 2.79μm electro-optically Q-switched Cr,Er:YSGG laser will be designed to obtain high beam quality and peak power output. The theoretical model of super-Gaussian beam pumped OPO will be modeled to analyze the effect factors of conversion efficiency for the OPO, and the design ideas and theory will be given for the high efficiency OPO system. By improving the parametric gain, we aim at achieving pulse energy of 40 mJ with 80% optical-to-optical conversion efficiency mid-infrared laser output, the tuning range is 4-7μm.The study in this project will provide research basis for the development of high beam quality Q-switching and high efficient OPO technology, and for the expanding of the application of the mid-infrared laser radiation.

中红外激光在光谱学、生物医疗、大气探测、光电对抗等领域有着重要的应用。为了获得高效率中红外激光输出，本项目提出采用超高斯分布的高光束质量、高峰值功率2.79μm激光作为ZGP-OPO泵浦源，解决目前中红外OPO因泵浦光的非均匀分布、逆转换及走离效应等因素导致的光光转换效率低的问题。设计基于超高斯输出耦合镜的2.79μm电光调Q Cr,Er:YSGG激光器，获得高光束质量的超高斯分布输出；建立超高斯分布光束泵浦OPO的理论模型，通过三波耦合方程深入分析影响参量转换过程的物理因素，给出高转换效率OPO系统的设计思路和理论，提高参量转换的非线性增益，获得光光转换效率80%、脉冲能量40mJ的中红外4-7μm可调谐激光输出。本项目的研究将为发展超高斯分布泵浦源调Q技术和高转换效率光参量技术，拓展中红外激光的广泛应用提供研究基础。

中红外激光在光谱学、生物医疗、大气探测、光电对抗等领域有着重要的应用。本项目采用了超高斯分布的高峰值功率2.79μm激光作为ZGP-OPO泵浦源以获得高效率中红外激光输出，解决目前中红外OPO因泵浦光的非均匀分布、逆转换及走离效应等因素导致的光光转换效率低的问题。项目设计了基于高斯输出耦合镜的2.79μm电光调Q Cr,Er:YSGG激光器，获得了高峰值功率的平顶分布输出；利用该泵浦源激光器进行了2.79μm泵浦的ZGP-OPO实验研究，获得了光光转换效率31.2%、脉冲能量5.3mJ的中红外4-8μm可调谐激光输出。转换效率低于预期值是因为2.79μm泵浦的I型相位匹配角度与产生的闲频光的倍频角度很接近，且ZGP非线性系数大，使得产生的闲频光被消耗从而降低了转换效率，计算的相位匹配角度为该过程提供了理论依据。通过采用平顶光束泵浦光参量振荡器，发现输出光束的能量分布有了明显的提高，说明参量转换过程中的逆转换、走离效应等得到了明显的抑制。本项目的研究为发展超高斯分布泵浦源调Q技术和高转换效率光参量技术，拓展中红外激光的广泛应用提供了研究基础。