高功率连续光和波长可调谐Er∶CaF_(2)激光器  

High-Power Continuous-Wave and Tunable Er∶CaF_(2) Lasers

作　　者：杨钟海 张振 赵智刚 苏良碧[4] 刘兆军[1,2,3] Yang Zhonghai;Zhang Zhen;Zhao Zhigang;Su Liangbi;Liu Zhaojun(School of Information Science and Engineering,Shandong University,Qingdao 266237,Shandong,China;Key Laboratory of Laser&Infrared System(Shandong University),Ministry of Education,Qingdao 266237,Shandong,China;Shandong Provincial Key Laboratory for Laser Technologies and Applications,Qingdao 266237,Shandong,China;Artificial Crystal Research Center,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 201899,China)

机构地区：[1]山东大学信息科学与工程学院,山东青岛266237 [2]山东大学激光与红外系统集成技术教育部重点实验室,山东青岛266237 [3]山东省激光技术与应用重点实验室,山东青岛266237 [4]中国科学院上海硅酸盐研究所人工晶体研究中心,上海201899

出　　处：《中国激光》2024年第17期116-122,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(61925508,62205359,62375156);中国科学院稳定支持基础研究领域青年团队计划(YSBR-024)。

摘　　要：本文报道了一种高功率半导体激光二极管双端泵浦Er∶CaF_(2)连续激光器和宽波长调谐范围的中红外激光器。在单端泵浦的谐振腔系统中,当泵浦功率为19.7 W时,输出功率达到了3.54 W,斜率效率为19.6%;在双端泵浦的谐振腔系统中,当泵浦功率为32.5 W时,连续光输出功率达到了5.04 W,斜率效率为16.5%,中心波长为2799.27 nm。据笔者所知,这是目前所有报道的激光二极管泵浦掺铒氟化物晶体激光器实现的最高连续光功率。采用厚度为1、2、4 mm的MgF_(2)双折射滤光片,实现了波长可调谐范围分别为168.89、148.87、141.17 nm的Er∶CaF_(2)激光器,这是目前所有报道的掺铒氟化物晶体激光器中实现的最宽的波长可调谐范围。Objective In the mid-infrared region,erbium-doped lasers at 2.8µm have attracted significant attention owing to their wide applications in the medical treatment,detection,and military fields.The phonon energy of erbium-doped crystalline oxides(e.g.,Er∶YAG and Er∶YSGG)is high(860 cm-1 and 728 cm-1),which causes the self-termination phenomenon.The phonon energy of erbium-doped sesquioxides,such as Er∶Lu2O3 and Er∶Y2O3,is low(618 cm-1 and 597 cm-1)and the thermal conductivity of these materials is high.However,the fabrication of these active laser materials is complicated and expensive mainly due to their high melting temperature.Erbium-doped fluorides,such as Er∶YLF,Er∶CaF_(2),and Er∶SrF_(2),show lower phonon energy(560 cm-1,322 cm-1,and 280 cm-1)than sesquioxides,which can effectively suppress the non-radiative transition.Especially,the doped Er3+ions prefer to form clusters in CaF_(2)and SrF_(2) crystals.These spontaneous clusters can achieve strong energy transfer between Er3+ions with very low doping concentration(approximately 1%),accordingly obtaining a high-efficiency and high-power continuous-wave(CW)laser at 2.8µm.The emission spectrum of Er∶CaF_(2)and Er∶SrF_(2) crystals is wide,approximately 250 nm(from 2600 nm to 2850 nm),around 2.8µm.Therefore,spectral tuning of the Er∶CaF_(2)laser output wavelength is viable.Methods To obtain high-power CW laser,a dual-end pumped Er∶CaF_(2)laser is demonstrated[Fig.1(a)].The two pumping sources are wavelength-stabilized 976 nm fiber coupled laser diodes(LD)with a fiber core diameter of 105µm and a numerical aperture of 0.22.The pumping radiations are focused into the laser crystal by the optical coupling systems with a coupling ratio of 30∶60(L1∶L2)and 30∶75(L4∶L3),respectively.A plane-concave resonator with a cavity length of 23 mm is formed by a concave dichroic mirror(DM1)and a plane output coupler(OC).The DM1,with a radius of curvature of 50 mm,is AR coated(T=95%)for 960-980 nm and HR coated(R=99.8%)for 2.65-2.85µm.An OC with T=3

关 键 词：激光器 中红外固体激光器 Er∶CaF_(2)激光器 双端泵浦结构 可调谐激光器 双折射滤光片 

分 类 号：O436[机械工程—光学工程]