射频激励相移阵列谐振腔波导CO_2激光器输出特性研究

PHASE COUPLING OF RF EXCITED OPTICAL PHASE SHIFTED ARRAY RESONATOR SLAB WAVEGUIDE CO 2 LASERS

为保持器件结构紧凑型的同时获得稳定的高功率、高光束质量激光输出，将相移光学阵列谐振腔技术用于射频激励扩散型冷却板条波导ＣＯ２激光器．实验发现，该设计方案虽然波导结构为矩形宽波导，但是由于采用了具有相移阵列结构的全反射镜，获得的激光束输出空间分布具有阵列输出光束的基本特征．在波导截面为１ｍｍ×２０ｍｍ、增益介质长度为２０ｃｍ的波导结构条件下，获得了４６Ｗ的激光功率输出和１１３％的电光转换效率．激光束输出的远场空间分布呈空间压缩的极锐单峰．由于该结构具有的选模特性，远场为单峰空间分布特征的输出激光束具有很好的稳定性．建立了相应的理论模型并研究了实践中的可行性．研究了相移阵列谐振腔结构参数及其加工误差对激光器输出光束特性的影响。

Abstract In this paper, an optical array resonator with phase shifting end mirror has been combined with the RF excited diffusively cooled slab waveguide CO 2 lasers to obtain a desirable output laser beam with single peaked far field intensity distribution, which is highly spatially suppressed with the merits of high brightness and good characteristics of propagation. In the experiments, a maximum output power of 46 W and highest conversion efficiency of 11.3% have been obtained from a 200 mm gain length device. The laser beam intensity distribution acquired has similar characteristics to the ouptut beam from laser arrays due to the periodical structure of the phase shifting total reflector, and has an excellent stability due to the mode selection capability of this type of resonator. In this paper, theoretical analysis is also given, based on which corresponding theoretical model is established, the practical feasibility is shown, and the laser beam output with characteristics of in phase array mode is predicted. The systematical experimental investigation indicates the prominent influence of the parameters of the phase shifting array end mirror on the property of the output beam. Furthermore, the manufacturing errors of the phase shifted array resonator are analyzed and the analysis provides a theoretical guide to the design of this type of lasers.