GeSe2中强各向异性偏振相关的非线性光学响应  

Polarization-dependent nonlinear optical response in GeSe2

作　　者：欧阳昊 胡思扬 申曼玲 张晨希 程湘爱[1,2,3] 江天 Ouyang Hao;Hu Si-Yang;Shen Man-Ling;Zhang Chen-Xi;Cheng Xiang-Ai;Jiang Tian(College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,China;State Key Laboratory of Pulsed Power Laser Technology,Changsha 410073,China;Hunan Provincial Key Laboratory of High Energy Laser Technology,Changsha 410073,China)

机构地区：[1]国防科技大学前沿交叉学科学院,长沙410073 [2]脉冲功率激光技术国家重点实验室,长沙410073 [3]高能激光技术湖南省重点实验室,长沙410073

出　　处：《物理学报》2020年第18期149-158,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11802339,11805276,61805282,61801498,11804387,11902358);国防科技大学科学研究基金(批准号:ZK16-03-59,ZK18-01-03,ZK18-03-36,ZK18-03-22);湖南省国家科学基金(批准号:2016JJ1021);脉冲功率激光技术国家重点实验室开放董事基金(批准号:SKL2018ZR05);湖南省高能技术重点实验室开放研究基金(批准号:GNJGJS03);激光与物质相互作用国家重点实验室开放基金(批准号:SKLLIM1702);青年人才培养项目(批准号:17-JCJQ-QT-004)资助的课题.

摘　　要：二硒化锗(GeSe2)作为一种层状Ⅳ-Ⅵ族半导体,具有面内各向异性结构及宽能带间隙,表现出了独特的光、电及热学性能.本文利用偏振拉曼光谱和线性吸收谱分别对GeSe2纳米片的晶轴取向和能带特性进行表征,并以此为依据采用微区I扫描系统研究了GeSe2在共振能带附近的光学非线性吸收机制.结果表明,GeSe2中非线性吸收机制为饱和吸收与激发态吸收的叠加,且对入射光偏振与波长均有强烈的依赖.近共振激发(450 nm)条件下,激发态吸收对偏振的依赖程度比较大,随着入射光偏振的不同,非线性调制深度可由4.6%变化至9.9%;而非共振激发(400 nm)时,该调制深度仅由7.0%变化至9.7%.同时,相比于饱和吸收,激发态吸收的偏振依赖程度受远离共振激发波长的影响而变化更大.Germanium diselenide(GeSe2),a layered Ⅳ-Ⅵ semiconductor,has an in-plane anisotropic structure and a wide band gap,exhibiting unique optical,electrical,and thermal properties.In this paper,polarization axis Raman spectrum and linear absorption spectrum are used to characterize the crystal axis orientation and energy band characteristics of GeSe2 flake,respectively.Based on the results,a micro-domain I scan system is used to study the optical nonlinear absorption mechanism of GeSe2 near the resonance band.The results show that the nonlinear absorption mechanism in GeSe2 is a superposition of saturation absorption and excited state absorption,and is strongly dependent on the polarization and wavelength of incident light.Under nearresonance excitation(450 nm),the excited state absorption is more greatly dependent on polarization.With different polarizations of incident light,the modulation depth can be changed from 4.6% to 9.9%;for nonresonant excitation(400 nm),the modulation depth only changes from 7.0% to 9.7%.At the same time,compared with saturation absorption,the polarization-dependent excited state absorption is greatly affected by the distance away from the resonance excitation wavelength.

关 键 词：各向异性 激发态吸收 微区I 扫描 

分 类 号：TN304.24[电子电信—物理电子学]