Versatile mid-infrared frequency-comb referenced sub-Doppler spectrometer

Year: 2018

Authors: Gambetta A., Vicentini E., Coluccelli N., Wang Y., Fernandez TT., Maddaloni P., De Natale P., Castrillo A., Gianfrani L., Laporta P., Galzerano G.

Autors Affiliation: Politecn Milan, Dipartimento Fis, Piazza Leonardo Vinci 32, I-20133 Milan, Italy; CNR, Ist Foton & Nanotecnol, Piazza Leonardo Vinci 32, I-20133 Milan, Italy; CNR INO, Via Campi Flegrei 34, I-80078 Pozzuoli, NA, Italy; INFN, Sez Napoli, Ist Nazl Fis Nucl, Complesso Univ MS Angelo, Via Cintia, I-80126 Naples, Italy; CNR INO, Largo Enrico Fermi 6, I-50125 Florence, Italy; Univ Campania Luigi Vanvitelli, Dipartimento Matemat & Fis, Viale Lincoln 5, I-81100 Caserta, Italy.

Abstract: We present a mid-IR high-precision spectrometer capable of performing accurate Doppler-free measurements with absolute calibration of the optical axis and high signal-to-noise ratio. The system is based on a widely tunable mid-IR offset-free frequency comb and a Quantum-Cascade-Laser (QCL). The QCL emission frequency is offset locked to one of the comb teeth to provide absolute-frequency calibration, spectral-narrowing, and accurate fine frequency tuning. Both the comb repetition frequency and QCL-comb offset frequency can be modulated to provide, respectively, slow- and fast-frequency-calibrated scanning capabilities. The characterisation of the spectrometer is demonstrated by recording sub-Doppler saturated absorption features of the CHF3 molecule at around 8.6 micron with a maximum signal-to-noise ratio of 7e103 in 10 s integration time, frequency-resolution of 160 kHz, and accuracy of less than 10 kHz.

Journal/Review: APL PHOTONICS

Volume: 3 (4)      Pages from: 046103-1  to: 046103-9

More Information: – The authors acknowledge financial support from the Italian Ministry of University and Research, FIRB Project No. RBFR1006TZ, and ELI Nuclear Physics (ELI-NP) infrastructure.
KeyWords: Calibration; Quantum cascade lasers; Spectrometers, Absolute calibration; Emission frequency; Frequency resolutions; High signal-to-noise ratio; Mid-infrared frequency combs; Repetition frequency; Saturated absorptions; Spectral narrowing, Signal to noise ratio; optical frequency comb; fluoroform
DOI: 10.1063/1.5025135

Citations: 7
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