气流方向Z型折叠离轴混合非稳腔研究  

Off-Axis Hybrid Unstable Resonator with Z-Fold in Gas Flow Direction

作　　者：李卿 刘现魁[1] 任晓明[1] 邱雄飞[1] 李金雪[1] 郭建增[1] Li Qing;Liu Xiankui;Ren Xiaoming;Qiu Xiongfei;Li Jinxue;Guo Jianzeng(The 718th Research Institute of China Shipbuilding Industry Corporation,Handan 056027,Hebei,China)

机构地区：[1]中国船舶重工集团公司第七一八研究所,河北邯郸056027

出　　处：《中国激光》2022年第23期39-45,共7页Chinese Journal of Lasers

基　　金：国家高技术发展计划(51326010201)。

摘　　要：提出并研究了一种气流方向Z型折叠离轴混合非稳腔,应用在小型化DF气流化学激光装置中(增益体积为30 mm×40 mm×125 mm),实现了平均功率550 W、光束质量β值1.8(稳定腔方向β值为1.5,非稳定腔方向β值为1.9)、光谱覆盖3680~4089 nm的中红外连续激光输出。该腔在气流方向是平凹稳定腔,并且进行了Z型折叠以减小稳定腔方向上的增益尺寸;在高度方向是正支共焦非稳腔。针对稳定腔方向上远场光斑从高阶横模振荡到基横模振荡的物理过程进行了理论计算与实验研究,光腔振荡的计算结果与实验结果吻合较好。计算与实验结果表明,气流方向Z型折叠离轴非稳腔可用在小型化、紧凑型DF气流化学激光装置中,实现高功率、高光束质量中红外连续激光输出。Objectivee t Hybrid unstable resonators have been widely used in slab solid-state lasers and gas laser systems in recent years duo their high extraction efficiency and high beam quality.So far,hybrid unstable resonators have not been used in DF gas flow chemical laser devices to achieve high-power,high-beam quality mid-infrared continuous wave(CW)laser output.In addition,the beam quality in the direction of stable resonator is always poor and hard to handle,and the physical process of far-field spot from high-order transverse mode oscillation to single fundamental transverse mode oscillation should be studied theoretically and experimentally.Methods A kind of off-axis hybrid unstable resonator with Z-fold in the flow direction is proposed and studied.The Z-folded off-axis hybrid unstable resonator is a flat concave stable resonator in the gas flow direction,and Z-folded to reduce the gain size in the direction of the stable resonator.In the height direction,it is a positive branch confocal unstable resonator,as shown in Fig.1.The magnification in the direction of unstable cavity is 1.2.The gain medium is generated by the DF gain generator driven by combustion.Nitrogen is used as diluent,and the static pressure of the gain air flow is generally less than 666.7 Pa.The gain size is about 30 mm in the air flow direction and 40 mm in the height direction,and the gain length of the laser single pass is 125 mm,while after Z-folding the gain length becomes 375 mm.The virtual assembly diagram of the gain generator module and the optical cavity module is shown in Fig.2.Figure 3 shows the schematic diagram of the monitoring optical path,with which the output power,far-field spot,output spectrum and near-field spot are monitored.We calculate the oscillatory self-reproducing modes of Z-folded off-axis hybrid unstable cavities by means of fast Fourier transform based on the diffraction theory of plane-wave angular spectra.In the calculation,the seed beam used for the optical cavity oscillation is a rectangular parallel plane w

关 键 词：激光器 离轴混合非稳腔 DF气流化学激光 光束质量 中红外激光 

分 类 号：O436[机械工程—光学工程]