A comprehensive review on the development and applications of narrow-linewidth lasers

With high-temporal coherence and low-phase noise, narrow-linewidth lasers have important applications in spectroscopy, holography, and coherent detection. At present, ultra-narrow-linewidth lasing is generated by solid-state, optical fiber, and semiconductor lasers, which serve as a good light source for scientific research and industrial applications. In this article, we summarize the fundamental techniques and review recent developments in narrow-linewidth lasers. Moreover, typical applications of narrow-linewidth lasers are discussed to provide reliable and easy-to-use references for comparing the performance of narrow-linewidth lasers.