Lasers with narrow linewidths and single frequencies are widely used in fields such as radar detection, nonlinear optics, and precision measurements. The demand for such lasers has promoted the rapid development of single-longitudinal-mode (SLM) selection technology. Here, we highlight the working principles of current mainstream SLM selection technologies and the recent advances in the field. We compare the characteristics of different SLM selection methods and list the challenges faced by these technologies.

中文翻译：

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固体激光器单纵模选择技术的发展

窄线宽、单频的激光器广泛应用于雷达探测、非线性光学、精密测量等领域。对此类激光器的需求推动了单纵模（SLM）选择技术的快速发展。在这里，我们重点介绍当前主流 SLM 选择技术的工作原理和该领域的最新进展。我们比较了不同 SLM 选择方法的特点，并列出了这些技术面临的挑战。