高能量、窄线宽两波耦合双腔ZGP-OPO中红外参量研究

Mid-infrared laser have important applications in fields such as the military, scientific research and the environment, to achieve high-resolution remote detection and target feature recognition, we need to develop high-energy, narrow linewidth mid-infrared optical parametric technology. To the problem of high threshold by inserting dispersion components and complex laser system by seed injection in the usual narrow linewidth OPO, we design a integrative two-wave coupling dual-cavity, utilizing self-made 2μm EO Q-switched Cr:Tm:Ho:YAG laser as the OPO pump source, using the self-grown high damage threshold ZGP crystal as mid-infrared OPO nonlinear crystal, carried out high energy and narrow linewidth research in ZGP-OPO, and achieving the linewidth of 0.1-0.3cm-1 and energy of 10mJ output. Exploring the mechanism of two-wave coupling with double resonant oscillation(DRO) and spectral broadening, building physical model of two-wave coupling with DRO, exploring the way to compress spectrum,building two-wave coupling dual-cavity laser oscillating equation, studying the dynamic characteristics and spectral characteristics of DRO.Giving relations between the two-wave gain, oscillation threshold, phase matching, conversion efficiency and the cavity parameters and pump parameters, providing the research base for promoting the application of the high energy and narrow linewidth mid-infrared laser technology and development of self-grown mid-infrared ZGP nonlinear crystal.

中红外激光在军事、环境和科研等领域有着重要的应用，为了实现高分辨率远程探测和目标特性识别，需要发展高能量、窄线宽中红外参量技术。针对通常窄线宽光参量振荡器中插入色散元件阈值高（能量小）、注入种子激光系统复杂等问题，本项目提出一体化两波耦合双腔，利用自主研制的2μm电光调Q Cr:Tm:Ho:YAG激光器作为OPO泵浦源，选用自主生长的大尺寸高损伤阈值ZGP晶体作为中红外参量非线性晶体，开展高能量、窄线宽ZGP-OPO中红外参量研究，实现0.1-0.3cm-1、10mJ的中红外激光输出。探索两波耦合双谐振振荡和光谱展宽机理，建立两波耦合双谐振振荡物理模型，探索谱线压缩方法，建立两波耦合双腔激光振荡方程，研究双谐振振荡器的动力学特性和光谱特性，给出两波增益、振荡阈值、相位匹配、转换效率与腔结构参数和泵浦参数的关系，为推进高能量、窄线宽中红外激光技术应用和自主ZGP非线性晶体发展提供研究基础。

中红外激光在光谱学、生物医疗、大气探测及光电对抗等领域有着重要的应用，为了实现高分辨率远程探测和目标特性识别，需要发展高能量、窄线宽中红外参量技术。本课题针对ZGP-OPO系统，开展了从高质量泵浦源、高品质ZGP晶体、高效率OPO系统到窄线宽输出的关键技术研究。以高效率、窄线宽ZGP-OPO为目标，自主研制了高峰值功率的2.09和2.79μm电光调Q激光器作为OPO泵浦源，设计研发了高损伤阈值LGS电光调Q开关，突破了该波段高峰值功率电光调Q的难题。研究了相位失配、逆转换及空间走离等对参量转换的影响规律，提出了高效率OPO系统的设计思路和方法，设计出了与高光束质量的2.09μm泵浦源相匹配的高效率ZGP-OPO光学系统，获得了脉冲能量19mJ的3-5μm可调谐中红外参量激光输出，光-光转换效率达到75.7%，创下了新的纪录。计算分析并设计了两波耦合腔中光栅和标准具的参数，实验验证了利用信号光间接压窄闲频光线宽的可行性，为推进高效率、高能量、窄线宽中红外激光技术应用和自主ZGP非线性晶体发展提供了研究基础。