The extremely short lifetime of optical transitions between electronic states in the conduction band (intersubband transitions) favors an ultrafast gain dynamic and the generation of optical combs. In article number 1900389, Etienne Rodriguez, Qi Jie Wang, Carlo Sirtori, and co‐workers show that by modulating the laser at its round‐trip frequency, it is possible to generate new longitudinal modes in the spectrum and to tune the free‐spectral‐range while keeping a comb‐like regime.

中文翻译：

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量子级联激光器：通过向中红外量子级联激光器中注入微波来实现自由光谱范围的可调性（Laser Photonics Rev. 14（5）/ 2020）

导带中电子状态之间的光学跃迁（子带间跃迁）的极短寿命有利于超快增益动态和光学梳的产生。Etienne Rodriguez，Qi Wang Wang，Carlo Sirtori及其同事在编号1900389中的研究表明，通过以往返频率调制激光，可以在光谱中产生新的纵向模式并调谐自由光谱保持梳子状的范围。