离轴非稳腔导引光多光束干涉与远场图样研究  

Multi⁃Beam Interference and Far⁃Field Pattern of Guiding Light in Off⁃Axis Unstable Resonator

作　　者：李卿 刘现魁 任晓明 郭俊杰 李洪春 刘常春 郭建增 Li Qing;Liu Xiankui;Ren Xiaoming;Guo Junjie;Li Hongchun;Liu Changchun;Guo Jianzeng(The 718th Research Institute of China State Shipbuilding Corporation Limited,Handan 056027,Hebei,China;Hebei Province Key Laboratory of Chemical and Gas Laser,Handan 056027,Hebei,China)

机构地区：[1]中国船舶集团有限公司第七一八研究所,河北邯郸056027 [2]河北省化学与气体激光重点实验室,河北邯郸056027

出　　处：《中国激光》2024年第6期67-73,共7页Chinese Journal of Lasers

摘　　要：研究光腔内导引光的往返振荡物理过程与传播特性有助于理解、判断光腔的准直失调状态。离轴非稳腔作为一种兼具高提取效率与高光束质量的混合非稳腔,调腔导引光在离轴非稳腔中的振荡物理过程研究鲜有报道。通过理论计算与实验研究了导引光在离轴非稳腔内的多光束干涉过程及其远场传播特征,在实验中搭建了离轴非稳腔(X方向为平凹稳定腔,Y方向为共焦非稳腔)导引光研究装置,通过凹球面镜小孔注入波长为632.8 nm的基模高斯光束,开展了光腔准直与导引光远场图样研究,实验结果与计算结果吻合较好。计算与实验结果表明:离轴非稳腔的干涉图样与传统共焦非稳腔/稳定腔不同,调腔导引光在腔镜小孔注入处出现椭圆“水滴”状干涉图样,该图样亮度较高,可以用于判断光腔的准直状态。输出导引光的远场光斑在Y方向上是不同振荡阶次的亮核光斑,其中高阶次亮核光斑可用于指示红外激光的远场光斑位置。Objective The collimation adjustment of an unstable resonator requires guiding light.Examination of the oscillation process and propagation characteristics of guiding light assists in the understanding and judgment of the resonator misalignment state.Off-axis unstable resonators are hybrid unstable resonators with high extraction efficiencies and beam quality values.The physical process of guiding light oscillation in an off-axis unstable resonator has rarely been investigated.Therefore,this study investigates the multibeam interference process and far-field propagation characteristics of guiding light in an off-axis unstable resonator using theoretical calculations and experiments.Methods A guiding light research device in an off-axis unstable resonator is constructed.The schematic of optical path of guiding light in the off-axis unstable resonator composed of four resonator mirrors is shown in Fig.1.The convex cylindrical mirror in the Ydirection and concave spherical mirror form a stable resonator in the X-direction and a positive-branch confocal unstable resonator in the Y-direction,respectively.Z-shaped folding in the X-direction is achieved by turning plane mirrors.The curvature radii of the concave spherical and convex cylindrical mirrors are 16 m and 14 m,respectively.The magnification in the direction of the unstable resonator is 1.14.The 632.8 nm He-Ne laser(guiding light)is injected through a small hole at the bottom of the concave spherical mirror,oscillates back and forth inside the resonator,and outputs off-axis in the Y-direction of the convex cylindrical mirror.The output guiding light is focused on the charge coupled device(CCD)target through a convex lens with 300 mm focal length to observe its far-field characteristics.In terms of numerical calculations,this study utilizes the diffraction theory of the plane wave angle spectrum to calculate the oscillation process of guiding light in a Z-shaped folded off-axis unstable resonator.In the calculations,the incident beam is a fundamental-mode Gaussi

关 键 词：激光光学 离轴非稳腔 多光束干涉 调腔方法 远场光斑 

分 类 号：O436[机械工程—光学工程]