Multi-correlation Fourier transform spectroscopy with the resolved modes of a frequency comb laser

An instrument achieving 100 KHz spectral precision using multiple correlation Fourier transform spectroscopy has been demonstrated. The instrument can measure the individual frequency comb modes of 100 MHz frequency comb lasers in air. The experiments show approximate to 400,000 resolved modes at linewidths of 85 MHz in the region of 829 nm and approximate to 182,000 resolved modes at linewidths of 28 MHz in the region of 1.5 m, with a recording time of few minutes. The precision of the instrument, defined by the frequency positioning, attains sub-MHz even when the scan is performed in air.