Abstract

Dual-comb spectroscopy (DCS) is a multi-heterodyne interferometric technique that employs two optical frequency combs (OFCs) with different line spacing. When DCS is carried out with a pair of mode-locked OFCs, the need of a tight phase locking between them leads to sophisticated hardware and/or software implementations [1]. A strategy to simplify the DCS architecture, demonstrated with several comb modalities, is the use of a bidirectional laser cavity to produce two counter-propagating combs, each one having different line spacing [2,3]. Alternatively, but offering much more flexibility on the mode separation, electro-optic (EO) frequency combs can also be used for carrying out DCS. In that DCS scheme, both EO combs are fed by a single cw laser, which ensures by default a high degree of mutual coherence between them [4].

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