Laser spectroscopy of hot atomic vapours: from ’scope to theoretical fit

Abstract

The spectroscopy of hot atomic vapours is a hot topic. Many of the work-horse techniques of contemporary atomic physics were first demonstrated in hot vapours. Alkali-metal atomic vapours are ideal media for quantum-optics experiments as they combine: a large resonant optical depth; long coherence times; and well-understood atom-atom interactions. These features aid with the simplicity of both the experimental set up and the theoretical framework. The topic attracts much attention as these systems are ideal for studying both fundamental physics and has numerous applications, especially in sensing electromagnetic fields and quantum technology. This tutorial reviews the necessary theory to understand the Doppler broadened absorption spectroscopy of alkali-metal atoms, and explains the data taking and processing necessary to compare theory and experiment. The aim is to provide a gentle introduction to novice scientists starting their studies of the spectroscopy of thermal vapours whilst also calling attention to the application of these ideas in the contemporary literature. In addition, the work of expert practitioners in the field is highlighted, explaining the relevance of three extensively-used software packages that complement the presentation herein.

Formation of strongly shifted EIT resonances using "forbidden" transitions of Cesium

“…(3) scientists working in the field of laser spectroscopy of alkali metal atoms about the MI atomic transitions. The above-mentioned MI transitions can be exploited in such high B-fields as new frequency markers, for using new frequency ranges, as well as for the frequency stabilization of lasers at strongly shifted frequencies from the initial transition in unperturbed atoms [13,14].…”

“…Therefore, the study of the peculiarities of atomic transitions (in particular Zeeman transitions in an external magnetic field) of alkali atoms is of utmost importance. It is well known that the application of a strong magnetic field can significantly change the probabilities (intensities) of the Zeeman transitions, as shown in [7][8][9][10][11][12][13]. High interest has recently been focused on atomic transitions between ground and excited levels that satisfy the condition F e − F g = ∆F = ±2 (these transitions are so-called forbidden by the selection rules, thus their probability is zero when no external magnetic field is applied).…”

How to build an optical filter with an atomic vapor cell

“…To linearize the absorption spectrum, we apply a peak finding routine to the recorded cavity peaks and fit an Airy-transmission function to the peaks' displacement. Pizzey et al [62] published a more extensive explanation of this method, which has been earlier described by Keaveney [63]. The second problem is power fluctuation induced by the frequency change of the scanning laser or due to polarization drifts in fibers.…”

“…There are several methods to even out the intensity fluctuations caused by the laser frequency scan. One is to even out the intensity fluctuations of the spectrum by the evaluation algorithm, explained in [62]. Our approach was to use a feedback loop to an intensity controller of an acousto-optical modulator.…”

Exploiting non-orthogonal eigenmodes in a non-Hermitian optical system to realize sub-100 MHz magneto-optical filters.

“…Of equal importance is the platform, particularly when filters are designed for use outside a laboratory setting. Most magnetooptical filters rely on thermal vapor cells due to their compact and resilient setups [50]. Thermal vapor filters can be tuned by varying the magnetic field, temperature and input polarization [51,52] and can switch between different D-line operation [53].…”