Terahertz (THz) frequencies remain among the least utilized in the electromagnetic spectrum, largely due to the lack of powerful and compact sources. The invention of THz quantum cascade lasers (QCLs) was a major breakthrough to bridge the so-called ‘THz gap’ between semiconductor electronic and photonic sources. However, their demanding cooling requirement has confined the technology to a laboratory environment. A portable and high-power THz laser system will have a qualitative impact on applications in medical imaging, communications, quality control, security and biochemistry. Here, by adopting a design strategy that achieves a clean three-level system, we have developed THz QCLs (at ~4 THz) with a maximum operating temperature of 250 K. The high operating temperature enables portable THz systems to perform real-time imaging with a room-temperature THz camera, as well as fast spectral measurements with a room-temperature detector.

太赫兹（THz）频率仍然是电磁频谱中使用最少的频率之一，这在很大程度上是由于缺乏强大而紧凑的信号源。太赫兹量子级联激光器（QCL）的发明是弥合半导体电子和光子源之间所谓的“太赫兹间隙”的重大突破。但是，他们苛刻的冷却要求将技术限制在实验室环境中。便携式高功率太赫兹激光系统将对医学成像，通信，质量控制，安全性和生物化学领域的应用产生定性影响。在这里，通过采用一种实现干净的三级系统的设计策略，我们开发了最高工作温度为250 K的THz QCL（约4 THz）。