通过圆偏振光提高飞秒激光诱导击穿光谱的发射强度  

Improving Emission Intensity of Femtosecond Laser-Induced Breakdown Spectroscopy by Using Circular Polarization

作　　者：于丹[1] 孙艳[1] 冯志书[2] 代玉银[3] 王秋云 陈安民[4] 金明星[4] Yu Dan;Sun Yan;Feng Zhishu;Dai Yuyin;Wang Qiuyun;Chen Anmin;Jin Mingxing(Basic Aviation College,Air Force Aviation University,Changchun,Jilin 130022,China;Aviation Operations Service College,Air Force Aviation University,Changchun,Jilin 130022,China;Nuclear Medicine Department,the First Hospital of Jilin University,Changchun,Jilin 130021,China;Institute of Atomic and Molecular Physics,Jilin University,Changchun,Jilin 130012,China)

机构地区：[1]空军航空大学航空基础学院,吉林长春130022 [2]空军航空大学作战勤务学院,吉林长春130022 [3]吉林大学第一医院核医学科,吉林长春130021 [4]吉林大学原子与分子物理研究所,吉林长春130012

出　　处：《中国激光》2021年第1期172-179,共8页Chinese Journal of Lasers

基　　金：国家自然科学基金(11674128,11674124,11974138);吉林省教育厅“十三五”科学技术研究规划项目(JJKH20200937KJ)。

摘　　要：激光诱导击穿光谱(LIBS)是一种快速、实时的元素成分分析技术。为了提高LIBS的灵敏度,人们已经提出多种方法来提高LIBS的光谱强度。本文采用飞秒脉冲激光烧蚀黄铜产生LIBS,对比了圆偏振和线偏振下LIBS光谱的强度,结果发现圆偏振下的光谱强度比线偏振下的强,光谱强度大约提高了15%。采用飞秒激光照射金属时,金属内部的自由电子吸收光子的能量。在线偏振飞秒激光场中,电子在脉冲的每个光学周期中经历交替的加速和减速;而圆偏振飞秒激光可以连续加速电子,因此电子可以获得更高的能量,这使得圆偏振飞秒激光产生的光谱强度不同于线偏振飞秒激光产生的光谱强度,圆偏振激光有助于改善飞秒LIBS信号的强度。Objective Laser-induced breakdown spectroscopy(LIBS)is a novel atomic-emission spectroscopic technique that has been widely used for the elemental analysis of materials.Investigators in the field of LIBS research are actively working to improve the sensitivity of this technique,and many methods have been proposed to enhance its spectral intensity.With the development of chirped-pulse-amplification technology,femtosecond pulse lasers have been introduced into the study of LIBS.Compared with nanosecond lasers,femtosecond lasers have many advantages for LIBS,but it is important to improve their spectral intensity.In general,the output laser beam of a femtosecond laser system is linearly polarized.In a linearly polarized laser field,electrons undergo alternating acceleration and deceleration in each optical period of the laser pulse.However,femtosecond lasers with circular polarization can accelerate electrons continuously,so they attain higher energies.The energies of electrons after irradiation with a circularly polarized femtosecond laser beam are different from those of electrons after irradiation with a linearly polarized femtosecond laser beam.This makes the optical signal from a plasma induced by a circularly polarized femtosecond laser beam different from that induced by a linearly polarized femtosecond laser beam.It is therefore necessary to compare the plasma emission induced by a femtosecond laser under both linear and circular polarizations.Methods We focused a femtosecond laser beam onto the surface of a brass sample to produce plasmas,and we analyzed the resulting plasma spectra.To compare the effects of linear and circular polarizations on the spectralemission intensity,we adjusted the polarization of the femtosecond laser beam from linear polarization to circular polarization by using a quarter-wave plate.The sample was placed on a three-dimensional translation table to avoid over-ablation.We collected the light emission from the laser-induced plasma and focused the collected light into an optical fib

关 键 词：光谱学 激光诱导击穿光谱 飞秒激光 圆偏振 光谱增强 

分 类 号：O657.3[理学—分析化学]