单腔双光梳激光器及其光谱学应用研究进展

光频梳因频率等间隔、波长稳定、谱线线宽窄以及谱宽大等特性，在高精度测量和计量中具有广泛的应用。其中，双光梳快速测量包括光谱测量、绝对测距、三维成像和超快异步光学采样等已成为研究热点之一。近年来，基于自由运行的单腔双光梳激光器的双梳光谱学系统由于具有结构简单、测量范围大和精度高等优点而备受关注。首先从时域和频域介绍了光频梳的特性和应用，尤其介绍了双光梳测量的优势，相较目前主流的稳频稳相锁模激光器、电光调制等双光梳光源实现方案，单腔双光梳激光器方案有望避免采用复杂的电子控制系统，简化双光梳光源的结构、体积和成本。因此，重点介绍了波长复用、偏振复用、空间复用和脉冲波形复用的单腔双光梳光纤激光器实现技术，并对其基本原理、性能参数和当前研究的进展以及目前发展中仍然存在的问题进行了分析；同时对保偏光纤双光梳激光器的研究现状及其性能进行了总结。接着，重点介绍了双梳光谱学的测量原理，回顾了现有光谱扩展技术，并详细介绍了基于自由运行的单腔双光梳激光器的双梳光谱学应用案例，包括掺铒光纤激光器所在的近红外波段以及其扩展到中红外和太赫兹波段的光谱探测。最后，总结了目前的单腔双光梳激光器的主要发展趋势，包括进一步提高单腔型双光梳激光腔的重频稳定性、降低共模噪声、探索单腔双光梳系统在中红外以及太赫兹波段的应用，推动单腔双光梳锁模光纤激光器的实用化。

A Review of Single-Cavity Dual-Comb Laser and Its Application in Spectroscopy

Optical frequency comb is widely used in high precision measurement and metrology because of its characteristics such as constant frequency interval, wavelength stability, narrow spectral line width and wide spectral band width. Among them, the fast dual-comb measurement, including spectroscopy, absolute ranging, 3D imaging and ultra fast asynchronous optical sampling, has become one of the research hotspots. The dual-comb spectroscopy system based on free-running single-cavity dual-comb laser has attracted much attention due to its advantages of simple structure, large measurement range and high accuracy. This article first introduces the features of the optical frequency comb in the time domain and frequency domain andits application, especially the advantages of the dual-comb measurement. Compared with the current mainstream dual-comb source schemes, such as frequency-stabilized and phase-locked mode-locked laser, electro-optic modulation and so on, the single-cavity dual-comb laser scheme is expected to avoid the use of complex electronic control system and simplify the structure and decrease the volume and the cost of the dual-comb source. Therefore, this paper mainly introduces single-cavity dual-comb fiber laser technology with wavelength-multiplexing, polarization-multiplexing, space-multiplexing and pulse-shape-multiplexing, and analyzes the basic principles, performance parameters and current research progress, as well as the existing problems in the current development of these technologies. Moreover, the researches and performances of polarization-maintaining fiber dual-comb lasers with higher stability are summarized. Then, this paper introduces the principle of dual-comb spectroscopy, reviews the current spectral extension technology, and introduces some application cases of dual-comb spectroscopy based on the free-running single-cavity dual-comb laser in detail, including the near infrared band of the erbium-doped fiber laser and the detection extended to mid-infrared and terahertz bands. Finally, we summarize the development trends of single-cavity dual-comb lasers, including further improving frequency stability of single-cavity dual-comb lasers, decreasing the common-mode noise of single-cavity lasers, exploring the application of single-cavity dual-comb system in mid-infrared and terahertz band, and making single-cavity dual-comb mode-locked fiber laser to be practical.