Abstract

Dual optical frequency combs have received increasing attention in recent years as they can be used in many applications involving a delay scan between the two pulse trains and dual-comb spectroscopy (DCS) [1]. For DCS there is interest in generating long-wavelength sources to access the molecular fingerprint region where many molecules have numerous absorption lines. Modelocked Cr:ZnS(e) laser sources are a promising route since they can directly access the 2 µm wavelength region and can be combined with efficient nonlinear frequency conversion to access the full fingerprint region [2]. To date, DCS in the region has been performed by two separate laser sources [3], recently including full stabilization of both combs [4]. For applications not needing absolutely calibrated comb lines, it is possible to significantly reduce the complexity of fully locked dual-combs by free-running dual-comb lasers [5]. By generating both combs in a single cavity, this approach leads to a simpler setup and overcomes the need for active feedback due to the high correlation between the combs. Here we present two optical frequency combs from a single semiconductor saturable absorber mirror (SESAM) modelocked Cr:ZnS laser cavity for the first time.

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