基于L形空间折叠光栅镜谐振腔的高功率径向偏振激光产生机理和方法研究

项目名称： 基于L形空间折叠光栅镜谐振腔的高功率径向偏振激光产生机理和方法研究

项目编号： No.61308045

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 无线电电子学、电信技术

项目作者： 李波

作者单位： 华中科技大学

项目金额： 25万元

中文摘要： 采用径向偏振光的CO2激光器切割金属效率大约是采用圆偏振光的两倍。本项目提出在轴快流CO2激光器上采用L形空间折叠激光谐振腔的结构形式和光栅镜的方法产生径向偏振光。由于轴快流CO2激光器具有对称性很好的增益区，且L形空间折叠激光谐振腔可以消除转折镜的偏振选择效应，可以得到稳定的高光束质量的径向偏振光。更重要的是采用光栅镜的方式，实现起来稳定可靠。本项目将增益等效模型和衍射积分理论结合起来，建立起等效的激光谐振腔模型并分析求解，得到光栅镜激光谐振腔输出的径向偏振光的模式特征。同时，研究光栅镜、增益区对激光模式的影响。优化光栅镜的结构参数，高效率的得到高功率高光束质量的径向偏振光。最终在轴快流CO2激光器上得到功率千瓦量级, 激光模式为TEM01*，偏振纯度大于90%的径向偏振光。径向偏振光还可应用于电子加速、扫描显微和粒子诱捕等许多尖端领域。

中文关键词： 径向偏振；L 形空间折叠谐振腔；光栅镜；轴快流 CO2 激光器；金属复合锥镜

英文摘要： The metal cutting efficiency of radial polarized laser is about twice the circular polarized laser. The project proposed a new method to produce high power raidal polarized laser using L-shaped space folded resonator and grating mirror in a fast-axial-flow CO2 laser. The fast-axial-flow CO2 laser has symmetry gain, and the polarization selection effect of folded mirrors can be eliminated in the L-shaped space folded resonator, the stable, high quality radial polarized laser can be got. More importantly, the grating mirror is stable and reliable. The gain equivalent model and diffraction integral theory are combined to establish an equivalent laser resonator model. The laser mode characteristics can be obtained by theoretical calculation. The influence on laser mode of grating mirror and gain distribution will be studied. The the structural parameters optimization of the grating mirror is made to obtain high power and high quality radial polarized laser. Finally, the raidal polarized laser can be obtained in a fast-axial-flow CO2 laser, the laser power is greater than 1kw, polarization purity>90%, TEM01* mode. Radial polarized laser can also be used in many cutting-edge areas, such as the electron acceleration, scanning microscopy and particle trapping.

英文关键词： radial polarization；L-shaped space folded resonator；grating mirror；fast-axial-flow CO2 laser；composite metal cone mirror