报告题目：High performance terahertz frequency quantum cascade lasers and their applications
报 告 人：Lianhe Li
Senior Research Fellow, School of Electronic and Electrical Engineering, University of Leeds
报告时间：2017年12月22日下午15:00-16:00
报告地点：清华大学刘卿楼402
主 持 人：赵自然  研究员
报告摘要：
Terahertz (THz) frequency radiation has many potential applications, ranging from imaging and chemical sensing through to telecommunications. However, one of the principal challenges has been to develop compact, low-cost, efficient THz sources. The demonstration of THz frequency quantum cascade laser (QCL) in 2002 provided a potential solid-state solution. Since then, THz QCLs have developed rapidly, offering frequencies from 1.2 to 5 THz; working temperatures up to 199.5 K; and peak optical output powers up to 2.4 W. Nowadays, it is the first powerful, compact, continuous wave, solid-state coherent THz radiation source. However, fabrication of THz QCLs is extremely challenging owing to the stringent demands for precise control of individual layer thickness and alloy composition, which must be maintained over the, typically, 10 µm thick active regions. Leeds has an international reputation for its agenda-setting research in THz QCLs over the last two decades. In 2014, we demonstrated the first THz QCLs with >1W output power; this has yet to be surpassed by any other group internationally, although we increased this further to > 2.4 W in 2017. In this talk, development and applications of these high performance THz QCLs will be discussed.

报告人简介：
Dr. Lianhe Li is currently with the school of Electronic and Electrical Engineering, University of Leeds. His research interest focuses on the molecular beam epitaxial growth and characterization of semiconductor materials and devices with particular emphasis on mid-infrared and terahertz (THz)-frequency light generation and detection. Recent research highlights including: the demonstration of the first THz QCL with > 1 W output power (winning the 2015 Electronic Letters Premium Award and listed as the highly cited paper by Web of Sciences); the introduction of photonic crystal structures and ‘spoof’ surface plasmons into THz QCLs to engineer the beam profile; a THz pulse amplifier based on a QCL cavity; the first active mode-locking of a THz QCL, coherent detection of emitted pulse trains from a THz QCL; and, a range of new THz QCL imaging/spectroscopy methodologies. He has co-authored over 200 high impact peer-review research papers in the most prestigious academic journals including Nature Photonics, Nature Materials and Nature Communications. He has also delivered over 100 contributed conference papers and held several awarded patents on device growths.

第256期“论坛”主请人联系方式：
赵自然  13910183037  zhaozr@tsinghua.edu.cn