Characterization and calibration of a Fourier-transform spectrometer using a laser frequency comb

Abstract

We have used a laser frequency comb with a repetition frequency of νrep≈1 GHz to measure the drift and dispersion of a Fourier-transform spectrometer (FTS). We used the electronic measurements of νrep and νCEO to create a reference line list. We measured 28 interferograms and computed the phase and power spectra. The analysis of the interferograms and phase spectra allowed for compensation of several spectroscopic artifacts. In the computed power spectra, we detected ∼64.000 suitable lines in the near-infrared bandwidth Δν=308.79–374.74 THz. The residual dispersion of the FTS can be described by two factors, a linear dispersion and a constant offset. Both are highly correlated and need to be computed simultaneously. The factors were computed from the comparison of a reference with measured line lists. The linear dispersion factor is found to be varying on the order of 10−8 Hz/Hz, while the constant offset is of the order of 107 Hz. Using two factors for calibration, the difference between the reference and the measured line list can be removed completely with an uncertainty of ∼65 kHz corresponding to a precision of 0.5·10−9 Hz/Hz.