Interband cascade lasers are power-efficient mid-infrared laser sources which usually exhibit a spectral linewidth of hundreds of kHz. However, narrower linewidth lasers are more desirable for high-resolution molecular spectroscopy applications. This work narrows the spectral linewidth of an interband cascade laser from about 530 kHz down to about 30 kHz by applying optical feedback from an external mirror. In contrast to common laser diodes, the linewidth reduction of interband cascade lasers does not require any feedback phase control, which significantly simplifies the experimental configuration, and hence, is highly favorable for practical applications.

中文翻译：

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具有光学反馈的 30 kHz 线宽带间级联激光器

带间级联激光器是高能效的中红外激光源，通常具有数百 kHz 的光谱线宽。然而，更窄线宽的激光器更适合高分辨率分子光谱学应用。这项工作通过应用来自外部反射镜的光学反馈，将带​​间级联激光器的光谱线宽从大约 530 kHz 缩小到大约 30 kHz。与普通激光二极管相比，带间级联激光器的线宽减小不需要任何反馈相位控制，这大大简化了实验配置，因此非常有利于实际应用。