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Title:Characterisation Of A 17 μm Quantum Cascade Laser And Spectroscopy Of The ν2 Fundamental Mode Of n2o
Author(s):Manceau, Mathieu
Contributor(s):Darquie, Benoit; Teissier, Roland; Tarbutt, Michael; Baranov, Alexei; Philippe, Hadrien; Wall, Thomas
Subject(s):Instrument/Technique Demonstration
Abstract:Owing to their narrow linewidth and broad tunability, continuous wave (CW) quantum cascade lasers (QCLs) have become ubiquitous for mid-infrared rovibrational molecular spectroscopy. However, while the 4-11 $\mu$m region is fairly well covered by available room-temperature QCLs, the extension to longer wavelengths is a challenge of great interest for molecular spectroscopy. Here we present spectroscopy measurements using a newly fabricated room temperature CW QCL working at $17$ $\mu$m, a new spectral region for QCLs \footnote{H. Nguyen Van, et al., “Long Wavelength ($\lambda > 17$ $\mu$m) Distributed Feedback Quantum Cascade Lasers Operating in a Continuous Wave at Room Temperature”, Photonics 6, 1, pp. 31 (2019).}, and delivering a few mWs of output power. We will describe our characterization of this laser, including measurements of its spectral range, frequency noise and linewidth. To do this, we park the laser on the side of a strong \chem{N_2O} absorption line which we use as a frequency-to-intensity converter. The frequency noise spectrum of the source is deduced from the measured intensity fluctuations. We have also demonstrated the QCL's capabilities by performing linear rovibrational absorption spectroscopy of the $\nu_2$ fundamental mode of \chem{N_2O} in a single-pass cell, covering the $580$ to $582.5$ cm$^{-1}$ spectral region. Doppler-limited and pressure-broadened lines are measured with various \chem{N_2O} pressures in the range from $1$ to $500$ Pa leading to a precise investigation of pressure broadening in this mode. We will finally discuss the potential of this source for precise measurements in ultra-cold diatomic species and for probing low energy vibrations in polyatomic molecules.
Issue Date:2021-06-22
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper / Presentation
Date Available in IDEALS:2021-09-24

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