应用于VCSEL的GaAs/AlO_(x)高折射率对比度亚波长光栅反射镜的设计和制备  

Design and Fabrication of GaAs/AlOx High-Index-Contrast Sub-Wavelength Grating Reflector for VCSEL

作　　者：罗妍 郝永芹 邹永刚 Luo Yan;Hao Yongqin;Zou Yonggang(National Key Laboratory of High Power Semiconductor Laser,Changchun University of Science and Technology,Changchun 130022,Jilin,China)

机构地区：[1]长春理工大学高功率半导体激光国家重点实验室,吉林长春130022

出　　处：《光学学报》2023年第1期9-14,共6页Acta Optica Sinica

基　　金：国家自然科学基金(11474038);吉林省科技发展计划(20200401073GX)。

摘　　要：基于严格耦合波理论,分析GaAs/AlO_(x)高折射率对比度亚波长光栅(HCG)反射镜的偏振和反射特性,设计了横电(TE)偏振的HCG。当入射光由衬底垂直入射时,HCG在940 nm附近的最高反射率接近1。分析了光栅形貌误差和入射角偏差对其反射特性的影响。采用金属有机化合物气相沉积技术进行外延生长,通过电子束曝光、干法刻蚀、湿法刻蚀以及湿法氧化等方法制备出HCG,并进行理论与实验结果的对比分析。实验测试了入射光由光栅表面垂直入射的反射率,其中TE偏振光的最高反射率达到84.9%,与86.5%的理论值比较接近,且横磁(TM)偏振光的反射率低于40%,反射谱的变化规律也与理论结果基本一致,这验证了理论结果的合理性。该反射镜可以作为垂直腔面发射激光器的超薄反射器,具有低损耗、偏振稳定和单模工作的特性。Objective The traditional vertical-cavity surface-emitting laser (VCSEL) uses distributed Bragg reflectors (DBRs) to provide high reflectivity to conform to the lasing standard.However,due to the relatively small refractive index contrast of lattice-matching material systems,many pairs of DBRs are needed to achieve high reflection,which brings difficulties and limitations to the manufacturing of VCSELs.In addition,multilayer DBRs can cause problems such as high impedance and low conversion efficiency.To improve the performance of VCSELs,researchers introduce the high-index-contrast subwavelength grating (HCG) as a reflector in the VCSEL.By the adjustment of grating parameters,it can have extremely high reflectivity and can replace the traditional DBRs in VCSEL.Hence,VCSELs with the HCG will not suffer from the problems of high resistance and serious light absorption caused by DBRs.In this paper,the HCG reflector for VCSELs is studied and fabricated.On the basis of the rigorous coupled wave analysis (RCWA),the polarization and reflection characteristics of a GaAs/AlO_(x)HCG reflector are analyzed.A TE-polarized HCG is designed to have the highest reflectivity of close to 1 near 940 nm when the incident light is perpendicular to the substrate.Moreover,the influences of topography error and the incident angle on reflectivity are investigated.Then,the device is prepared by mental-organic chemical vapor deposition technology,electron beam lithography (EBL),inductively coupled plasma (ICP) etching,wet etching,and wet oxidation.Since the GaAs/AlO_(x)HCG has the same material system as the half-VCSEL,it can be integrated with the VCSEL through one-time epitaxial technology,which is of great significance for obtaining high-quality wafers.Furthermore,the low stress between the HCG and half-VCSEL is crucial to keep the long-term stability of the device.Methods Fig.1 shows the structure of the HCG,including the grating layer H1,stress buffer layer H2,and low index sub-layer H3,which are directly grown on the GaAs substrate.T

关 键 词：光栅 高折射率对比度亚波长光栅 衍射效率 偏振 单模 垂直腔面发射激光器 

分 类 号：O472.8[理学—半导体物理]