Modelling spectra of hot alkali vapour in the saturation regime

Laser spectroscopy of hot atomic vapours has been studied extensively. Theoretical models that predict the absolute value of the electric susceptibility are crucial for optimising the design of photonic devices that use hot vapours, and for extracting parameters, such as external fields, when these...

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Main Authors: Daniel R Häupl, Clare R Higgins, Danielle Pizzey, Jack D Briscoe, Steven A Wrathmall, Ifan G Hughes, Robert Löw, Nicolas Y Joly
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:New Journal of Physics
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Online Access:https://doi.org/10.1088/1367-2630/adb77c
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author Daniel R Häupl
Clare R Higgins
Danielle Pizzey
Jack D Briscoe
Steven A Wrathmall
Ifan G Hughes
Robert Löw
Nicolas Y Joly
author_facet Daniel R Häupl
Clare R Higgins
Danielle Pizzey
Jack D Briscoe
Steven A Wrathmall
Ifan G Hughes
Robert Löw
Nicolas Y Joly
author_sort Daniel R Häupl
collection DOAJ
description Laser spectroscopy of hot atomic vapours has been studied extensively. Theoretical models that predict the absolute value of the electric susceptibility are crucial for optimising the design of photonic devices that use hot vapours, and for extracting parameters, such as external fields, when these devices are used as sensors. To date, most of the models developed have been restricted to the weak-probe regime. However, fulfilling the weak-probe power constraint may not always be easy, desired or necessary. Here we present a model for simulating the spectra of alkali-metal vapours for a variety of experimental parameters, most distinctly at intensities beyond weak laser fields. The model incorporates optical pumping effects and transit-time broadening. We test the performance of the model by performing spectroscopy of ^87 Rb in a magnetic field of 0.6 T, where isolated atomic resonances can be addressed. We find very good agreement between the model and data for three different beam diameters and a variation of intensity of over five orders of magnitude. The non-overlapping absorption lines allow us to differentiate the saturation behaviour of open and closed transitions. While our model was only experimentally verified for the D2 line of rubidium, the software is also capable of simulating spectra of rubidium, sodium, potassium and caesium over both D lines.
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spelling doaj-art-f6f9f8d29f0b4c8caadf998f760155a52025-08-20T02:59:08ZengIOP PublishingNew Journal of Physics1367-26302025-01-0127303300310.1088/1367-2630/adb77cModelling spectra of hot alkali vapour in the saturation regimeDaniel R Häupl0https://orcid.org/0000-0002-2446-4307Clare R Higgins1https://orcid.org/0000-0002-9835-8478Danielle Pizzey2https://orcid.org/0000-0002-9025-8608Jack D Briscoe3https://orcid.org/0000-0002-8878-0528Steven A Wrathmall4https://orcid.org/0000-0003-1770-9721Ifan G Hughes5https://orcid.org/0000-0001-6322-6435Robert Löw6Nicolas Y Joly7https://orcid.org/0000-0001-9654-4624University of Erlangen-Nürnberg , Staudtstraße 7/B2, 91058 Erlangen, Germany; Max Planck Institute for the Science of Light , Staudtstraße 2, 91058 Erlangen, GermanyDepartment of Physics, Durham University , South Road, Durham DH1 3LE, United KingdomDepartment of Physics, Durham University , South Road, Durham DH1 3LE, United KingdomDepartment of Physics, Durham University , South Road, Durham DH1 3LE, United KingdomDepartment of Physics, Durham University , South Road, Durham DH1 3LE, United KingdomDepartment of Physics, Durham University , South Road, Durham DH1 3LE, United Kingdom5th Physical Institute, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, GermanyUniversity of Erlangen-Nürnberg , Staudtstraße 7/B2, 91058 Erlangen, Germany; Max Planck Institute for the Science of Light , Staudtstraße 2, 91058 Erlangen, GermanyLaser spectroscopy of hot atomic vapours has been studied extensively. Theoretical models that predict the absolute value of the electric susceptibility are crucial for optimising the design of photonic devices that use hot vapours, and for extracting parameters, such as external fields, when these devices are used as sensors. To date, most of the models developed have been restricted to the weak-probe regime. However, fulfilling the weak-probe power constraint may not always be easy, desired or necessary. Here we present a model for simulating the spectra of alkali-metal vapours for a variety of experimental parameters, most distinctly at intensities beyond weak laser fields. The model incorporates optical pumping effects and transit-time broadening. We test the performance of the model by performing spectroscopy of ^87 Rb in a magnetic field of 0.6 T, where isolated atomic resonances can be addressed. We find very good agreement between the model and data for three different beam diameters and a variation of intensity of over five orders of magnitude. The non-overlapping absorption lines allow us to differentiate the saturation behaviour of open and closed transitions. While our model was only experimentally verified for the D2 line of rubidium, the software is also capable of simulating spectra of rubidium, sodium, potassium and caesium over both D lines.https://doi.org/10.1088/1367-2630/adb77catomic spectroscopyPaschen–Backatomic transitionsLindblad master equationcomputer modelsaturation intensity
spellingShingle Daniel R Häupl
Clare R Higgins
Danielle Pizzey
Jack D Briscoe
Steven A Wrathmall
Ifan G Hughes
Robert Löw
Nicolas Y Joly
Modelling spectra of hot alkali vapour in the saturation regime
New Journal of Physics
atomic spectroscopy
Paschen–Back
atomic transitions
Lindblad master equation
computer model
saturation intensity
title Modelling spectra of hot alkali vapour in the saturation regime
title_full Modelling spectra of hot alkali vapour in the saturation regime
title_fullStr Modelling spectra of hot alkali vapour in the saturation regime
title_full_unstemmed Modelling spectra of hot alkali vapour in the saturation regime
title_short Modelling spectra of hot alkali vapour in the saturation regime
title_sort modelling spectra of hot alkali vapour in the saturation regime
topic atomic spectroscopy
Paschen–Back
atomic transitions
Lindblad master equation
computer model
saturation intensity
url https://doi.org/10.1088/1367-2630/adb77c
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