Femtosecond time-resolved spectroscopy and frequency-comb spectroscopy have been individually developed to achieve better time and frequency resolutions, respectively. The two spectroscopic techniques have been developed for different systems, even though they use mode-locked laser in common. Recently, there was an interesting merge of the two techniques into a dual frequency-comb (DFC) spectroscopy, resulting in a new femtosecond spectroscopy with simple instrumentation and high data acquisition speed compared to conventional femtosecond spectroscopic techniques. By slightly detuning the repetition rates of two phase-locked frequency-comb lasers, both automatic time-delay scanning and parallel data recording with single point detectors are possible. Thus, we anticipate that the DFC spectroscopy would allow one to expand the application limits of the conventional femtosecond spectroscopic methods. In this Perspective article, we provide reviews of linear and nonlinear DFC spectroscopy theory and applications with a perspective on the development of coherent multidimensional frequency-comb spectroscopy.

飞秒时间分辨光谱学和频率梳状光谱学已经分别开发，分别获得了更好的时间和频率分辨率。两种光谱技术已针对不同的系统开发，即使它们共同使用锁模激光。最近，将这两种技术有趣地融合到了双频梳（DFC）光谱中，从而形成了一种新型飞秒光谱法，与传统的飞秒光谱技术相比，它具有仪器简单，数据采集速度快的特点。通过稍微降低两个锁相频率梳状激光器的重复频率，可以实现自动延时扫描和使用单点检测器的并行数据记录。因此，我们预计DFC光谱将允许人们扩大传统飞秒光谱方法的应用范围。在这篇“透视”文章中，我们将对线性和非线性DFC光谱理论和应用进行回顾，并对相干多维频梳光谱学的发展进行展望。