The slight differences between two optical frequency combs from the same laser source capture precise microwave intervals. Two different combs from a single source Combs of light divide the optical frequency spectrum into closely spaced tines that can measure molecular absorption spectra with exceptional precision. One appealing method to extend this precision down into the microwave regime is to simultaneously use two slightly distinct combs that differ in spacing by the magnitude of a microwave frequency. The challenge is ensuring that the combs remain synchronized. Link et al. solve this problem by generating both combs from the same semiconductor laser source. The resultant dual comb delivers highly accurate spectra of water vapor, and the approach could be generalized across the optical spectrum by tuning the semiconductor source. Science, this issue p. 1164 Dual-comb spectroscopy offers the potential for high accuracy combined with fast data acquisition. Applications are often limited, however, by the complexity of optical comb systems. Here we present dual-comb spectroscopy of water vapor using a substantially simplified single-laser system. Very good spectroscopy measurements with fast sampling rates are achieved with a free-running dual-comb mode-locked semiconductor disk laser. The absolute stability of the optical comb modes is characterized both for free-running operation and with simple microwave stabilization. This approach drastically reduces the complexity for dual-comb spectroscopy. Band-gap engineering to tune the center wavelength from the ultraviolet to the mid-infrared could optimize frequency combs for specific gas targets, further enabling dual-comb spectroscopy for a wider range of industrial applications.

中文翻译：

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使用自激半导体盘式激光器的水蒸气双梳光谱

来自同一激光源的两个光频梳之间的细微差别捕获了精确的微波间隔。来自单一光源的两个不同的梳状光梳将光频谱划分为紧密间隔的尖齿，可以非常精确地测量分子吸收光谱。将这种精度扩展到微波范围的一种吸引人的方法是同时使用两个稍微不同的梳子，它们的间距因微波频率的大小而异。挑战在于确保梳子保持同步。链接等。通过从同一个半导体激光源产生两个梳来解决这个问题。由此产生的双梳提供了高度准确的水蒸气光谱，并且可以通过调整半导体源在整个光谱范围内推广该方法。科学，这个问题 1164 双梳光谱提供高精度和快速数据采集的潜力。然而，应用通常受到光梳系统复杂性的限制。在这里，我们使用基本简化的单激光系统展示了水蒸气的双梳光​​谱。使用自由运行的双梳锁模半导体盘式激光器实现了具有快速采样率的非常好的光谱测量。光梳模式的绝对稳定性的特点是自由运行和简单的微波稳定。这种方法大大降低了双梳光谱的复杂性。将中心波长从紫外线调整到中红外线的带隙工程可以优化特定气体目标的频率梳，