摘要
基于近红外波段1064 nm激光的四倍频过程是产生深紫外激光的有效技术手段之一。然而,非线性晶体在产生深紫外激光的过程中,晶体内部严重的非线性吸收带来的热效应会破坏其相位匹配条件,进而制约深紫外激光功率的提升。为此,在利用偏硼酸钡(BBO)晶体作为1064 nm近红外光四倍频过程的非线性转化介质的基础上,通过对不同匹配温度下的晶体内部温升情况进行研究,发现提高晶体匹配温度可以有效减缓晶体内部由非线性吸收引起的热效应,改善深紫外激光功率输出。最终,在晶体匹配温度为180℃、绿光输入功率为16 W时,获得了重复频率为20 kHz、单脉冲宽度为4 ns、平均功率为2.56 W的266 nm深紫外激光。通过建立BBO晶体非线性吸收理论模型,进一步计算了不同匹配温度、不同紫外激光功率下的非线性吸收系数和归一化色心密度,结果显示,非线性吸收系数与紫外激光功率强度正相关,并且在紫外激光功率均为2.25 W时,相较于60℃,匹配温度为180℃的晶体其非线性吸收系数减小了近63%,色心密度也降低了57%,该研究结果对实现高功率的266 nm深紫外激光的输出具有重要意义。
Objective All-solid-state high-power deep ultraviolet (DUV) 266 nm lasers are widely employed in various fields,including Raman spectroscopy,photo-biological imaging,integrated circuit etching,and precision micromachining,owing to their compact structure,high single-photon energy,and good long-term stability.Thus far,the fourth harmonic generation (FHG) of a 1064 nm laser based on nonlinear crystals,including cesium lithium borate (CLBO) and barium metaborate (BBO),is the most widely adopted method for generating a DUV 266 nm laser.However,its significant nonlinear absorption results in a large temperature gradient inside the crystal,which prevents the complete phase matching of the entire crystal.Consequently,the output power of the DUV 266 nm laser saturates easily in experiments.Although many methods for alleviating nonlinear absorption and eliminating power saturation have been devised,one must comprehensively investigate the thermal characteristics of BBO crystals when they are used to generate highpower DUV 266 nm lasers.Therefore,in this study,the effects of the phase-matching temperature of BBO crystal on heat generation inside the crystal and the output power of a 266 nm laser are first investigated during FHG.Experimental data show that an increase in the phase-matching temperature can effectively alleviate the thermal effect caused by nonlinear absorption inside the crystal,thus improving the output power of the 266 nm laser.In particular,when the phase-matching temperature of the BBO crystal increases from 60℃to 180℃,the maximum output power of the 266 nm laser increases from 2.25 W to 2.56 W.Second,a theoretical model of nonlinear absorption is established to explain the experimental results,and the nonlinear absorption coefficient (βNLA) and normalized color center density at different phase-matching temperatures that affect heat generation in the crystal are calculated using the experimental data.This study provides an instructive reference for generating high-power 266 nm DUV lasers.Methods T
作者
王子文
曹雪辰
张艳林
程东林
靳丕铦
卢华东
Wang Ziwen;Cao Xuechen;Zhang Yanlin;Cheng Donglin;Jin Pixian;Lu Huadong(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of OptoElectronics,Shanxi University,Taiyuan 030006,Shanxi,China;Collaborative Innovation Center for Extreme Optics,Shanxi University,Taiyuan 030006,Shanxi,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2024年第14期26-34,共9页
Chinese Journal of Lasers
基金
国家自然科学基金(61975100,62105192)
国家重点研发计划(2022YFC2204003)
山西省杰出青年培育项目(202103021221004)
山西省留学基金委资助研究项目(2022-015)
山西省科技创新人才计划(202204051002005)
山西省专利转化专项计划项目(202305007)
山西省1331工程项目
第一实验室-国创中心(山西)科技创新项目。
关键词
266
nm深紫外激光
非线性吸收
热效应
匹配温度
高功率
偏硼酸钡
266 nm deep ultraviolet laser
nonlinear absorption
thermal effect
phasematching temperature
high power
barium metaborate
