报告题目：Ultracompact high-Q single-mode semiconductor lasers
报 告 人：Qijie Wang 教授（新加坡南洋理工大学）
主 持 人：刘涛 教授
报告时间：2025年5月22日（星期四）下午3：30
报告地点：物理与光电学院18楼213报告厅
主办单位：物理与光电学院
报告摘要：
Highly compact semiconductor lasers with a low threshold and stable single-mode operation are in great demand for integrated optoelectronics. However, considerable side leakages and radiation losses in small cavities substantially degrade the quality (Q) factor, posing a substantial significant obstacle in pursuing high-performance miniature lasers. Here we propose and experimentally demonstrate a flat-band laser supplemented by multiple bound states in the continuum. By simultaneously confining light in all three dimensions, a high Q factor of ~1,440 in an ultracompact terahertz quantum cascade laser cavity with a lateral size of ~3λ is reported [1]. The field confinement makes it possible to realize an electrically pumped single-mode terahertz laser with a low threshold current density, despite the small device footprint. This surface-emitting laser emits a well-defined beam with good directionality. The demonstrated multibound-state-assisted flat-band design is also applicable to other wavelength regimes, offering a route to energy-efficient, monolithically integrated and ultracompact laser sources that suit a wide range of applications.
[1] Jieyuan Cui, Song Han, Bofeng Zhu, Chongwu Wang, Yunda Chua, Qian Wang, Lianhe Li, Alexander Giles Davies, Edmund Harold Linfield, and Qi Jie Wang, Ultracompact multibound-state-assisted flat-band lasers, Nature Photonics, 2025. https://www.nature.com/articles/s41566-025-01665-6
报告人简介：
Prof. WANG Qijie is a full professor at the School of Electrical and Electronic Engineering (EEE) and the School of Physical and Mathematical Sciences (SPMS) NTU. He is an OPTICA Fellow. He is a co-recipient of the Institution of Engineers Singapore, Prestigious Engineering Achievement Team Award of Singapore Twice in 2005 and 2017, respectively, the prestigious Singapore Young Scientist Award 2014, Nanyang Research Award 2015 (Young Investigator), ARC Sciences Nanotechnology Medal and Prize, 2021, and NTU College of Engineering (CoE) Research Excellence Award, 2022. He is now the Associate Dean (Graduate Students) of CoE, NTU.