HBr空芯光纤气体激光器的振动热池多能级理论模型与设计仿真  

Vibrational thermal pool multi-level theoretical model and design simulation of HBr-filled hollow-core fiber gas laser

作　　者：危超 余炫 雷诚 王自昱 刘胜 王度 Wei Chao;Yu Xuan;Lei Cheng;Wang Zi-Yu;Liu Sheng;Wang Du(Institute of Technological Sciences,Wuhan University,Wuhan 430000,China)

机构地区：[1]武汉大学工业科学研究院,武汉430000

出　　处：《物理学报》2024年第15期71-79,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62075200,12374295);中央高校基本科研业务费专项资金(批准号:2042022gf0004,2042023kf0113)资助的课题

摘　　要：空芯光纤气体激光器已逐渐发展为一种重要的中红外激光光源,在实验上取得了良好进展,但现有的基于传统速率方程模型的理论设计方法仍不完善.本文提出了一种溴化氢(HBr)空芯光纤的振动热池建模方法,该模型可充分考虑空芯光纤气体激光器内振转弛豫对腔内增益特性的影响,计算显示激光斜效率、阈值和瓶颈效应与实验吻合良好.此外,基于该模型,本文探讨了脉冲泵浦的光子泄漏现象,通过引入泄漏因子,得到了与实验结果接近的脉冲波形的弛豫振荡和激光斜率效率,有效解决了脉冲泵浦模型中的泵浦溢出问题.本研究提出的振动热池理论模型可适用于各类气体填充的空芯光纤气体激光器.A The hollow-core fiber gas laser(HCFGL)has developed into a significant mid-infrared laser source,but the development of theoretical model still lags behind experimental progress.In this work,we propose a multi-level vibrational thermal pool(VTP)model of HBr-filled HCFs,which comprehensively considers the rovibrational relaxation effects on laser gain in reasonable approximations of transition coefficients,and studies the laser characteristics on multi-line lasing,bottleneck effect,line competition,etc.The VTP model shows more precise results of laser slope efficiency,and threshold than previous models while fitting the experimental data very well,and successfully predicts an output bottleneck at 1 W pump.The P-branch laser is relatively advantageous over the R-branch laser for its larger Einstein coefficient and emission cross section,and the seed injection can intensify the line competition and reach the highest P4 power proportion of 80%.The VTP model reveals that the output of various pump lines has a pattern similar to the Boltzmann distribution,suggesting that the distribution of ground rotational levels limits the laser gain of pump lines.Moreover,we discuss the photon leakage in high-energy pulsed pumping conditions.With the introduction of the leaking coefficient,this model shows relaxation oscillations and laser slope efficiencies close to experimental values and greater than the results in the CW condition,and solves the overpump problem in pulsed pump simulation.Finally,we confirm that the photon leakage is intensified at high repetition rate and the leaking coefficient should relate to the pulse repetition rate.This work develops a comprehensive modeling method for MIR laser simulation and this model is also applicable to various gas-filled HCFGLs.

关 键 词：气体激光 空芯光纤 中红外 速率方程仿真 

分 类 号：TN248[电子电信—物理电子学]