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Updated: Feb 25, 2026

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies
Published on: December 18, 2015
Dual-comb mid-infrared spectroscopy with free-running oscillators and absolute optical calibration from a
Abstract:
By using free-running independent femtosecond OPOs with a repetition-rate difference of 500 Hz we demonstrate methane absorption spectroscopy with spectral coverage simultaneously spanning the methane P, Q and R branches and with a resolution of 0.5 cm-1. Absolute optical frequency calibration with an accuracy of 0.25 cm-1 (0.27 nm) is achieved from simultaneous repetition-rate and carrier-envelope-offset frequency measurements, without the need for any optical reference. The calibration technique allows registration and averaging of consecutively acquired dual-comb spectra, leading to a high quality and low-noise absorbance measurement in good agreement with the HITRAN database.
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