Comb-locked deep-ultraviolet laser system for precision mercury spectroscopy

Year: 2024

Authors: Gravina S., Chishti NA., Castrillo A., Gianfrani L., Sorgi A., Pastor PC., Clivati C., Bertiglia F., Lopardo G., Levi F., Galzerano G.

Autors Affiliation: Univ Campania Luigi Vanvitelli, Dept Math & Phys, Viale Lincoln 5, I-81100 Caserta, Italy; CNR, Natl Inst Opt, Largo Enr Fermi 6, I-50125 Florence, Italy; Natl Inst Metrol Res, Str Cacce 91, I-10135 Turin, Italy; CNR, Inst Photon & Nanotechnol, Piazza Leonardo Vinci 32, I-20133 Milan, Italy.

Abstract: Doppler-broadening gas thermometry is extended to the deep-ultraviolet domain using a comb-locked laser frequency chain, expressly developed for precision spectroscopy of mercury vapors at the wavelength of 253.7 nm, in coincidence with the (6s2)1S0 -> (6s6p)3P1 intercombination line. The system is based on a double-stage second-harmonic generation process of an external-cavity diode laser at 1014.8 nm, which is frequency locked to a self-referenced optical-frequency-comb synthesizer by means of an efficient nonlinear frequency-mixing scheme. An absolute frequency axis in the UV region is produced by scanning the comb repetition rate, with the entire frequency chain following the reference comb tooth. The complete characterization of the phase noise of the comb-locked near-infrared laser demonstrates line-emission narrowing down to the limit imposed by the coherence of the comb teeth. After a proper processing of the phase noise, the Gaussian and Lorentzian components of the width of the UV radiation are determined. This is useful to estimate the instrumental perturbation to the probed mercury line for the aims of thermodynamic temperature metrology. In this regard, the preliminary spectroscopic results are quite promising, despite the difficulties arising from the short wavelength of operation.

Journal/Review: PHYSICAL REVIEW A

Volume: 109 (2)      Pages from: 22816-1  to: 22816-8

More Information: This research was funded by the Italian Ministry for Universities and Research (MUR) , under the Program PRIN2015, Project No. 20152MRAKH.
KeyWords: Frequency Noise; Constant
DOI: 10.1103/PhysRevA.109.022816

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