基于腔内球差选模产生高阶拉盖尔-高斯模式激光  

High-order Laguerre-Gaussian mode laser generated based on spherical aberration cavity

作　　者：刘俊杰 盛泉[1,2] 王盟[1,2] 张钧翔 耿兴宁 石争 王爱华 史伟 姚建铨[1,2] Liu Jun-Jie;Sheng Quan;Wang Meng;Zhang Jun-Xiang;Geng Xing-Ning;Shi Zheng;Wang Ai-Hua;Shi Wei;Yao Jian-Quan(School of Precision Instrument and Optoelectronics Engineering,Tianjin University,Tianjin 300072,China;Key Laboratory of Optoelectronic Information Science and Technology Ministry of Education,,Tianjin University,Tianjin 300072,China;Tianjin Jinhang Institute of Technical Physics,Tianjin 300308,China;Science and Technology on Electro-Optical Information Security Control Laboratory,Tianjin 300308,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,天津300072 [2]天津大学,光电信息技术教育部重点实验室,天津300072 [3]天津津航技术物理研究所,天津300308 [4]光电信息控制和安全技术重点实验室,天津300308

出　　处：《物理学报》2022年第1期116-122,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61975146)资助的课题。

摘　　要：本文报道了基于腔内球差在端泵Nd:YVO_(4)激光器中选择单一高阶拉盖尔-高斯(LG)振荡模式的实验研究.在激光谐振腔内使用短焦距透镜引入明显的球差,使具有不同光斑半径的各阶LG模式的光路在空间上发生分离,从而实现对模式的选择作用,1.03 W泵浦功率下线偏振1064 nm激光能够在LG_(0,)±10和LG_(0,)±33之间以单横模工作.分析发现适当的横模间球差是抑制边模、选择单一高阶LG模式的必要条件,而过大的球差又会导致单一LG模式自身遭受明显的损耗,不利于产生高阶的LG模式输出.据此进一步优化实验参数,获得了角向指数m达到±75的高阶LG模式输出.The high-order Laguerre-Gaussian(LG)mode output from an end-pumped Nd:YVO_(4) laser cavity with strong spherical aberration(SA)induced by short-focal-length lens is studied in this work.A long-focal-length lens L1 is used in the cavity to expand and collimate the beam,so that the beam incident on another short-focal-length lens L2 in the cavity undergoes a strong SA.Since the ring-shaped LG modes with different values of angular index m have different beam radii,the actual focal points of each order of beam are then spatially displaced.A flat output coupler(OC)is located near the focal point of L2,which is composed of a cat-eye retroreflector together with the lens.Such a retroreflector can provide only ideal retroreflection to the incident beam with a focal point exactly on the OC.Given the focal point displacements of the LG beams with different orders,such a mechanism can be used for implementing the transverse mode selection.The mode which has an actual focal point on the OC has a smaller loss than the other defocused modes.With an a-cut Nd:YVO4 as laser crystal,scalar(linear-polarized)single-mode LG output with radical index p=0 and angular index m>0 is obtained.The laser mode-order is selectable from LG_(0,)±10 to LG_(0,)±33 under 878.6-nm incident diode pump power of 1.03 W,by simply adjusting the distance between the OC and L2 in a range of 0.5 mm,when using lens L1 with f=150 mm and lens L2 of f=33.9 mm.It is found that sufficient SA which makes the optical paths of the neighboring modes well distinguishable is essential for single-mode operation of a wanted order of LG mode.However,too strong an SA can stop the high-order mode beam from oscillating,since the width and radius of the ring-shaped LG mode are an increasing function of indices p and m,which bring a stronger loss to the corresponding mode.Based on this analysis,we turn to a focal-length combination of f1=100 mm and f2=51.8 mm,to reduce the SA to a level suitable for further higher mode operation.A highest-order LG_(0,)±75 is obtained by su

关 键 词：拉盖尔-高斯模式 固体激光器 模式选择 球差 

分 类 号：TN24[电子电信—物理电子学]