基于单腔多模光纤锁模激光器的双光梳和多光梳及气体吸收谱测量应用

双光梳光谱技术是一种新兴的具有超高分辨率、高灵敏度及高采样率的宽带光谱测量技术，在气体吸收谱测量、温室气体排放监控、非线性光谱成像等诸多领域都有着重要应用。目前双光梳光源的产生方法存在稳频系统复杂、梳齿间距大或者制作工艺困难等缺点。而最近新兴的基于方向复用、波长复用或偏振复用的单腔双光梳技术克服了上述缺点，但依然存在重频差较小且难以调节的问题。本课题提出基于空间模式复用的单腔双光梳及多光梳技术，旨在解决以上难题。本课题将深入研究基于多模光纤激光器中多横模并行锁模的机理，研究不同空间模式之间的非线性相互作用，选择性地控制不同空间模式的损耗或增益，实现稳定且重频差可调控的双光梳和多光梳。采用时间展宽技术研究多模式耗散孤子的形成和相互作用的动力学过程。最后，利用研制的双光梳对HCN等气体吸收谱进行高相干、高速测量。本课题的开展将推动双光梳及多光梳多维光谱技术的发展，具有重要的科学意义和应用价值。

Dual-comb spectroscopy (DCS) is an emerging broadband spectroscopic technique that exhibits ultrahigh frequency resolution, accuracy, and sampling rate. DCS has significant applications in various areas, including gas absorption spectroscopy, greenhouse gas monitoring, nonlinear spectral imaging, and so on. Unfortunately, the generations of dual-comb sources reported so far exhibit many disadvantages, such as complex frequency stabilization systems, large comb spacing, or difficult and complicated fabrication processes. Recently, the emerging dual-comb sources from a single-cavity based on direction-, wavelength- or polarization-multiplexing can overcome some shortcomings described above, however, these approaches still possess weaknesses of small and uncontrollable repetition rate difference. In order to circumvent these disadvantages, we propose dual- and multiple-comb from a single cavity based on multiplexing of different spatial-mode mode-locking in a passively multimode mode-locked fiber laser. We will deeply explore the mechanism underlying the parallel individual mode-locking of multi-spatial modes in a single-cavity. The mechanism of nonlinear interaction between different spatial modes will be thoroughly investigated. In addition, we will selectively control the gain or loss of different modes for stable dual- and multiple-comb and adjustable repetition rate difference. Moreover, time-stretch technique will be adopted to explore the physical nature of dual- and multiple-comb and multimode dissipative solitons. Finally, absorption spectroscopy of multiple gas molecules, for example, hydrogen cyanide, will be measured by using our mode-multiplexing dual-comb. This project will promote the development of dual- and multiple-comb-based multidimensional spectroscopy and will have a significant impact on scientific research and applications.