基于遗传算法的快轴流CO_(2)激光放大器的参数优化  

Optimization of Fast Axial Flow CO_(2)Laser Amplifier Parameters Based on Genetic Algorithm

作　　者：游聪 黄维 林高洁 李波[1] 赵江 胡友友 You Cong;Huang Wei;Lin Gaojie;Li Bo;Zhao Jiang;Hu Youyou(School of Optics and Electronic Information,Huazhong University of Science and Technology,Wuhan 430074,Hubei,China;School of Microelectronics,Hubei University,Wuhan 430062,Hubei,China;College of Science,Jiangsu University of Science and Technology,Zhenjiang 212003,Jiangsu,China)

机构地区：[1]华中科技大学光学与电子信息学院,湖北武汉430074 [2]湖北大学微电子学院,湖北武汉430062 [3]江苏科技大学理学院,江苏镇江212003

出　　处：《中国激光》2024年第7期203-210,共8页Chinese Journal of Lasers

摘　　要：获得13.5 nm极紫外光刻光源的主流方案为激光激发等离子体,即利用高功率、高重复频率、高光束质量的短脉冲CO_(2)激光与液滴锡靶作用产生极紫外光。高功率CO_(2)激光由振荡器产生的高重复频率CO_(2)种子经多级放大产生,所以功率放大器是驱动光源系统的核心器件之一。建立了射频激励快轴流CO_(2)激光放大器的六温度模型,可以模拟计算放大过程中稳态与瞬态的能量分布情况、光强变化情况、增益系数等。以此模型为适应度函数,采用遗传算法对自研射频激励快轴流CO_(2)激光放大器的腔压和CO_(2)、N_(2)、He气体体积比进行全局优化,优化结果为80 mbar(1 bar=100 kPa)和V(CO_(2))∶V(N_(2))∶V(He)=12.2%∶15.3%∶72.5%。在波长10.6μm种子光注入功率110 W的情况下,放大器的激光输出功率从2504 W提高到3422 W,验证了该方法的可行性和有效性。Objective The mainstream approach for obtaining a 13.5 nm extreme ultraviolet(EUV)lithography light source involves laserexcited plasma.This requires the use of a high-power,high-frequency,and high-beam-quality short-pulse CO_(2)laser,as well as a droplet Sn target,to generate extreme ultraviolet light.To satisfy the power requirements of EUV lithography,a high-frequency CO_(2)oscillator must be used to generate high-frequency CO_(2)seeds.These seeds undergo multi-stage amplification to produce a high-power CO_(2)laser that serves as the driving laser.Consequently,a power amplifier is the core device for driving a light source system.Therefore,this study aims to optimize the operating parameters of a radio frequency(RF)-excited fast axial-flow CO_(2)laser power amplifier to achieve better gain performance and higher amplified output power.This optimization has significant practical significance for efficiently obtaining EUV light sources.Methods Generally,the output power of an RF-excited fast axial laser amplifier is intricately linked to several factors such as the seed optical power,gas composition ratio,RF injection power,discharge tube diameter,gas pressure,and flow rate.In this paper,we establish a six-temperature model for an RF-excited fast axial CO_(2)laser amplifier.This model encompasses the most abundant energy levels for simulating and calculating steady-state and transient energy distributions,light intensity changes,gain coefficients,etc.in the amplification process.As optimizing a single parameter with a six-temperature model may result in local optimization and a considerable workload,we employ a global optimization approach for the amplifier.Multiple parameters of the amplifier are optimized simultaneously.Thus,a six-temperature model serves as the fitness function,and a genetic algorithm is applied to globally optimize the cavity pressure and gas pressure ratio of CO_(2)∶N_(2)∶He in a self-developed RF-excited fast axial CO_(2)laser amplifier.Furthermore,by continuously adjusting the releva

关 键 词：激光技术 极紫外 CO_(2)激光放大 六温度模型 遗传算法 

分 类 号：TN24[电子电信—物理电子学]