AUTHOR=Li Weijiang , Li Yuanyuan , Ma Yu , Xu Yunfei , Liu Junqi , Zhuo Ning , Lu Quanyong , Wang Lijun , Zhang Jinchuan , Zhai Shenqiang , Liu Shuman , Liu Fengqi TITLE=Continuous-wave terahertz quantum cascade laser based on a hybrid bound to bound quantum design JOURNAL=Frontiers in Photonics VOLUME=3 YEAR=2022 URL=https://www.frontiersin.org/journals/photonics/articles/10.3389/fphot.2022.1071879 DOI=10.3389/fphot.2022.1071879 ISSN=2673-6853 ABSTRACT=

We report a low threshold power density and high power output terahertz quantum cascade laser emitting at ∼3.9 THz operating in continuous-wave mode. The high output power and wall-plug efficiency are achieved based on a hybrid bound-to-bound quantum active design. A record output power of 312 mW and a low threshold power density of 0.8 kW/mm3 (threshold current density of 109 A/cm2) in continuous-wave mode at 20 K is demonstrated for a 300-μm-wide and 2-mm-long single-ridge device. The highest wall-plug efficiency is 1.38% and the slope efficiency is 684 mW/A with an internal quantum efficiency of ∼120 photons per injected electron. The demonstration of this low-threshold and high-power THz laser will promote THz-based remote sensing and standoff detection for pharmaceutical and health industry applications.