增益分布对GaN基蓝光微盘激光器模式分布和发光功率的影响  

Effect of gain distribution on mode distribution and luminescence power of GaN-based blue microdisk lasers

作　　者：许湘钰 刘召强 贾童 楚春双 张勇辉 张紫辉[1,2,3] Xu Xiangyu;Liu Zhaoqiang;Jia Tong;Chu Chunshuang;Zhang Yonghui;Zhang Zihui(School of Electronic and Information Engineering,Hebei University of Technology,Tianjin 300401,China;Tianjin Key Laboratory of Electronic Materials and Devices,Hebei University of Technology,Tianjin 300401,China;Hebei Key Laboratory of Advanced Laser Technology and Equipment,Hebei University of Technology,Tianjin 300401,China)

机构地区：[1]河北工业大学电子信息工程学院,天津300401 [2]河北工业大学天津市电子材料与器件重点实验室,天津300401 [3]河北工业大学河北省先进激光技术与装备重点实验室,天津300401

出　　处：《红外与激光工程》2024年第1期136-143,共8页Infrared and Laser Engineering

基　　金：国家自然科学基金项目(62074050,62275073,61975051);河北省自然科学基金项目(F2020202030)。

摘　　要：通过FDTD仿真模拟计算,文中系统地研究了电流阻挡作用对GaN基蓝光激光器增益分布和光学性能的影响,发现回音壁激光模式主要在靠近微盘边缘1.5个波长范围谐振,因此,如果电流阻挡层面积太小,无法最大化减小激光器电流阈值;如果面积太大,回音壁激光模式与无增益区存在耦合效应,从而减少激光功率。另外,随着无增益区域向微盘边缘发生偏移,各个激光模式输出的峰值功率均下降,其中二阶模式峰值功率比一阶模式下降得更加显著,这主要是由于二阶模式分布范围更接近微盘中心区域。同时,进一步发现如果在微盘激光器的仿真模型中引入侧壁缺陷,则将导致边缘无法形成增益区,相比于二阶模式而言,一阶模式的发光功率随侧壁缺陷区域增加而下降的幅度更为显著,这主要是由于一阶模式分布范围更接近微盘边缘。Objective The GaN-based microdisk laser based on whispering-gallery modes(WGMs)has the characteristics of high power,low threshold and small size.It has a wide-ranging application prospects and is needed in many fields such as optoelectronic integration,biomedicine and data transmission.However,due to the lack of conductive substrates and poor material grown quality,GaN-based microdisk lasers have long been dominated by light-injected microdisk devices.To achieve an electrically-driven GaN-based microdisk laser,a current block layer is typically introduced in the central region of the microdisk laser.This allows for injection of current only at the edge of the microdisk,resulting in that the low threshold laser output can be achieved,and the heat generation in the central region can be well suppressed.Although the effect of the central current block layer has been reported,there is a lack of sufficient reports on the effect of current block layer size on the microdisk laser and its design guidelines.In this paper,the effect of the gain distribution affected by the current block layer design on the performance of blue laser is systematically investigated.Methods According to the structure of the reported blue microdisk laser,the device structure of this study is designed(Fig.1(a)).The gain material in the active region is set as the Lorentz gain material,the real and imaginary part curves of the refractive index are obtained by setting the material parameters(Fig.1(b)-(c)).The Finite-Difference Time-Domain simulation(FDTD)is used to analyze the effect of the gain distribution on the performance of the blue laser.The no-gain circle region represents the area where current is unable to inject due to the presence of current block layer Results and Discussions Firstly,the performance of the microdisk laser is studied by changing the diameter of no-gain circle region,and the resonance of the device is simulated by FDTD(Fig.3).The results show that there are five distinct modes,all of which exhibit a gradually decrease

关 键 词：激光器 微盘 增益 FDTD 

分 类 号：TN365[电子电信—物理电子学]