Dual frequency comb spectroscopy with a single laser

We demonstrate a simple scheme for dual frequency comb spectroscopy in which the second frequency comb is generated by propagating the primary pulse train through a dazzler. The two frequency combs are combined behind a Mach-Zehnder interferometer, and the optical spectrum is read out by an rf-spectrum analyzer. The method is applied to record the overtone absorption spectrum of C2H2 (acetylene) in the wavelength region around 1.03 μm. A spectrum with a resolution of 4  cm(-1) is obtained, which compares well with that from the HITRAN database. A simple method for improving the spectral resolution is demonstrated.