Li Yuyin, Chen Peng, Zhang Xianfei, Yan Ziwen, Xu Tong, Xie Zili, Xiu Xiangqian, Chen Dunjun, Zhao Hong, Shi Yi, Zhang Rong, Zheng Youdou
Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.
Nanomaterials (Basel). 2023 Aug 1;13(15):2228. doi: 10.3390/nano13152228.
Low-threshold lasing under pulsed optical pumping is demonstrated in GaN-based microrod cavities at room temperature, which are fabricated on the patterned sapphire substrates (PSS). Because the distribution of threading dislocations (TDs) is different at different locations, a confocal micro-photoluminescence spectroscopy (μ-PL) was performed to analyze the lasing properties of the different diameter microrods at the top of the triangle islands and between the triangle islands of the PSS substrates, respectively. The μ-PL results show that the 2 μm-diameter microrod cavity has a minimum threshold of about 0.3 kW/cm. Whispering gallery modes (WGMs) in the microrod cavities are investigated by finite-difference time-domain simulation. Combined with the dislocation distribution in the GaN on the PSS substrates, it is found that the distribution of the strongest lasing WGMs always moves to the region with fewer TDs. This work reveals the connection between the lasing modes and the dislocation distribution, and can contribute to the development of low-threshold and high-efficiency GaN-based micro-lasers.
在室温下，基于氮化镓的微柱腔在脉冲光泵浦下实现了低阈值激光发射，这些微柱腔是在图案化蓝宝石衬底（PSS）上制备的。由于不同位置的穿透位错（TDs）分布不同，分别采用共焦微光致发光光谱（μ-PL）来分析PSS衬底三角形岛顶部和三角形岛之间不同直径微柱的激光特性。μ-PL结果表明，直径为2μm的微柱腔具有约0.3kW/cm的最小阈值。通过时域有限差分模拟研究了微柱腔中的回音壁模式（WGMs）。结合PSS衬底上氮化镓中的位错分布，发现最强激光WGMs的分布总是向TDs较少的区域移动。这项工作揭示了激光模式与位错分布之间的联系，并有助于开发基于氮化镓的低阈值、高效率微激光器。
