大口径超低吸收系数中红外磷锗锌晶体与器件制备  

Fabrication of Mid-Infrared ZnGeP_(2) Crystals and Devices with Large Apertures and Ultra-Low Absorption Coefficients

作　　者：袁泽锐[1,2] 窦云巍 方潘[1,2] 陈莹 尹文龙 康彬[1,2,3] Yuan Zerui;Dou Yunwei;Fang Pan;Chen Ying;Yin Wenlong;Kang Bin(Institute of Chemical Materials,China Academy of Engineering Physics,Mianyang,Sichuan 621999,China;Sichuan Research Center of New Materials,Chengdu,Sichuan 610200,China;Key Laboratory of Science and Technology on High Energy Laser,China Academy of Engineering Physics,Mianyang,Sichuan 621999,China)

机构地区：[1]中国工程物理研究院化工材料研究所,四川绵阳621999 [2]四川省新材料研究中心,四川成都610200 [3]中国工程物理研究院高能激光科学与技术重点实验室,四川绵阳621999

出　　处：《中国激光》2022年第1期240-243,共4页Chinese Journal of Lasers

基　　金：中国工程物理研究院化工材料研究所重点项目(989901832)。

摘　　要：光参量振荡(OPO)技术是目前实现全固态可调谐高功率3~5μm中红外激光的主流方案,其核心是红外非线性光学晶体,晶体品质决定红外激光功率水平。磷锗锌(ZnGeP_(2),ZGP)晶体性能优异,被称为“中红外非线性光学晶体之王”,但在0.7~2.2μm附近存在异常的光学吸收带,这阻碍了ZGP OPO功率的进一步提升。针对这一问题,采用自制的梯度冷凝炉,结合超低梯度冷凝技术,生长出3.8~5.0 cm大尺寸ZGP单晶,通过定向、切割、退火、抛光、镀膜等处理后,成功实现了多种规格OPO器件的生产,最大器件尺寸达30 mm×30 mm×40 mm,器件在波长2.09μm和1.064μm处的吸收系数分别低至0.015 cm^(-1)和0.4 cm^(-1)。采用单块超低吸收ZGP OPO器件,实现了3~5μm高功率中红外激光输出,功率达107 W,斜率效率为75%,光光效率为61.8%,光束质量(M^(2))为3.1左右。Objective Nowadays,the optical parametric oscillator(OPO)technique through mid-infrared nonlinear optical(NLO)crystals is an important way to generate tunable high power all-solid-state 3-5μm mid-infrared laser sources which have many important civil and military applications including atmospheric monitoring,medical diagnosis,and photoelectric countermeasures.In OPOs,the infrared nonlinear optical crystal is critical as itsquality determines the output power of a mid-infrared laser.Zinc germanium phosphide,ZnGeP_(2)(ZGP),possesses a high nonlinear coefficient,a high damage threshold,and good thermal conductivity and is transparent and phase matchable at 2μm,and thus it is called“the king of mid-infrared nonlinear optical crystals”.However,there is an abnormal optical absorption band in the wavelength region of 0.7-2.2μm that hinders the output power increase of ZGP OPOs.In order to meet the demands of applications that require higher efficiencies and output powers,absorption losses at the abnormal optical absorption band have to be further reduced.Methods A highly-pure polycrystalline ZGP is synthesized by using a self-made two-zone tube furnace.Large ZGP single crystals are grown by the gradient freezing method.ZGP OPO devices are fabricated after orienting,cutting,post-growth thermal annealing,polishing,and coating.A spectrophotometer is used to measure the spectrum of ZGP.The OPO laser experiment is carried out with one ZGP device pumped by a 2.09μm Ho:YAG pulsed laser with a pulse repetition rate of 20 kHz.Results and Discussions In this study,high quality large ZGP single crystals with diameters of 3.8-5.0 cm have been successfully grown by the freezing method with an ultralow gradient(0.5-1℃/cm)in the self-made furnaces with growth yields over 95%.Figs.1(a)and(b)show the ZGP crystals grown by HGF and VGF,respectively.The ZGP OPO crystal devices with various specifications[Figs.1(c)and(d)]are fabricated with the maximum size up to 30 mm×30 mm×40 mm(the largest ZGP OPO device fabricated to date)af

关 键 词：激光技术 中红外非线性光学晶体 ZnGeP_(2)单晶 超低梯度冷凝法 高功率中红外激光 

分 类 号：TN248.1[电子电信—物理电子学]