Comb-calibrated sub-Doppler spectroscopy with an external-cavity quantum cascade laser at 77 μm

Bidoor Alsaif, Davide Gatti, Marco Lamperti, Paolo Laporta, Aamir Farooq, Marco Marangoni

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We study the frequency noise and the referencing to a near-infrared frequency comb of a widely tunable external-cavity quantum-cascade-laser that shows a relatively narrow free-running emission linewidth of 1.7 MHz. The frequency locking of the laser to the comb further narrows its linewidth to 690 kHz and enables sub-Doppler spectroscopy on an N2O transition of the ν1 band near 7.7 μm with sub-MHz resolution and absolute frequency calibration. The combined uncertainty on the measured transition center is estimated to be less than 50 kHz
Original languageEnglish (US)
Pages (from-to)23785
JournalOptics Express
Issue number17
StatePublished - Aug 5 2019

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