Continuous-wave terahertz quantum cascade laser based on a hybrid bound to bound quantum design
Weijiang Li, Yuanyuan Li, Yu Ma, Yunfei Xu, Junqi Liu, Ning Zhuo, Quanyong Lu, Lijun Wang, Jinchuan Zhang, Shenqiang Zhai, Shuman Liu, Fengqi Liu
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/mm 3 (threshold current density of 109 A/cm 2 ) 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.