The phenomenon of self-pulsation (SP) in terahertz (THz) quantum cascade lasers (QCLs) due to optical feedback was reported recently. In this Letter, we propose a THz imaging modality using the SP phenomenon in a THz QCL. We explore the theoretical oscillation properties of the SP scheme and demonstrate its suitability to perform imaging experimentally. The SP imaging scheme operates in self-detection mode, eliminating the need for an external detector. Moreover, the scheme requires only a fixed current, meaning that one can avoid many of the pitfalls associated with high temperature operation of THz QCLs, including frequency chirp and mode hops caused by sweeping the laser current. This also means that one is free to locate the operating point at the maximum power, to produce the desired beam profile or for highest spectral purity, depending on the application. The SP imaging modality proposed in this work can be translated directly to high operating temperature THz QCLs.

中文翻译：

---

光反馈下量子级联激光器中具有自脉动的太赫兹成像

最近报道了由于光反馈引起的太赫兹 (THz) 量子级联激光器 (QCL) 中的自脉动 (SP) 现象。在这封信中，我们提出了一种使用太赫兹 QCL 中的 SP 现象的太赫兹成像模式。我们探索了 SP 方案的理论振荡特性，并证明了其在实验上进行成像的适用性。SP 成像方案在自检测模式下运行，无需外部检测器。此外，该方案仅需要固定电流，这意味着可以避免与 THz QCL 的高温操作相关的许多缺陷，包括扫描激光电流引起的频率啁啾和模式跳跃。这也意味着人们可以自由地将工作点定位在最大功率，以产生所需的光束轮廓或最高的光谱纯度，取决于应用程序。这项工作中提出的 SP 成像模式可以直接转换为高工作温度 THz QCL。