Abstract

Dual-comb interferometry (DCI) is a measurement technique that has been proven very useful for many applications such as spectroscopy, ranging, or fiber sensing. It relies on the interference in a photodetector of two mutually coherent optical frequency combs (OFCs) with slightly different repetition frequencies. The result is a down-converted RF comb whose teeth are evenly spaced by the difference of the repetition rates of the two OFCs. DCI enables a high-resolution measurement of a device under test by a single and fast acquisition, using a setup with no moving parts and low-bandwidth electronics. The resolution of the technique is limited by the comb spacing. For this reason, many efforts have been made to reduce the frequency separation of the comb lines [1] which is usually larger than tens of MHz.

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