Voigt transmission windows in optically thick atomic vapours: a method to create single-peaked line centre filters

Briscoe, Jack Daniel; Logue, Fraser D.; Pizzey, Danielle; Wrathmall, Steven A.; Hughes, Ifan G.

doi:10.1088/1361-6455/acc49c

Cited by 3 publications

(2 citation statements)

References 75 publications

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“…Both cells are heated by a resistive heater and situated in a large magnetic field, orientated in the appropriate geometry. A field strength of ≈0.6 T is achieved using two NdFeB top hat magnets [70], and therefore the atoms reside in the hyperfine Paschen-Back regime [52,56,67,74]. Before entering the cell, light is linearly polarised in the horizontal direction via the combination of a half-waveplate and Glan-Taylor polariser (GTP).…”

Section: Experiment: Measuring the Refractive Indices Of A Birefringe...mentioning

confidence: 99%

“…the relative angle between the light wavevector ⃗ k and the magnetic field vector ⃗ B), and solve for two cases of analytic magneto-optical rotation. These are the Faraday geometry [58,61,[66][67][68], where ⃗ k is parallel to ⃗ B ( ⃗ k ∥ ⃗ B), and the Voigt geometry [45,[69][70][71][72][73][74][75], where ⃗ k is perpendicular to ⃗ B ( ⃗ k ⊥ ⃗ B). The HT technique is applied to both of these systems, leading to an indirect measurement of the two refractive indices n 1,2 for each geometry via simple absorption spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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Indirect measurement of atomic magneto-optical rotation via Hilbert transform

Briscoe,

Pizzey,

Wrathmall

et al. 2024

J. Phys. B: At. Mol. Opt. Phys.

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The Kramers-Kronig relations are a pivotal foundation of linear optics and atomic physics, embedding a physical connection between the real and imaginary components of any causal response function. A mathematically equivalent, but simpler, approach instead utilises the Hilbert transform. In a previous study, the Hilbert transform was applied to absorption spectra in order to infer the sole refractive index of an atomic medium in the absence of an external magnetic field. The presence of a magnetic field causes the medium to become birefringent and dichroic, and therefore it is instead characterised by two refractive indices. In this study, we apply the same Hilbert transform technique to independently measure both refractive indices of a birefringent atomic medium, leading to an indirect measurement of atomic magneto-optical rotation. Key to this measurement is the insight that inputting specific light polarisations into an atomic medium induces absorption associated with only one of the refractive indices. We show this is true in two configurations, commonly referred to in literature as the Faraday and Voigt geometries, which differ by the magnetic field orientation with respect to the light wavevector. For both cases, we measure the two refractive indices independently for a Rb thermal vapour in a 0.6 T magnetic field, finding excellent agreement with theory. This study further emphasises the application of the Hilbert transform to the field of quantum and atomic optics in the linear regime.

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Section: Experiment: Measuring the Refractive Indices Of A Birefringe...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Indirect measurement of atomic magneto-optical rotation via Hilbert transform

Briscoe,

Pizzey,

Wrathmall

et al. 2024

J. Phys. B: At. Mol. Opt. Phys.

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A device for magnetic-field angle control in magneto-optical filters using a solenoid-permanent magnet pair

Alqarni,

Briscoe,

Higgins

et al. 2024

Review of Scientific Instruments

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Atomic bandpass filters are used in a variety of applications due to their narrow bandwidths and high transmission at specific frequencies. Predominantly, these filters are in the Faraday (Voigt) geometry, using an applied axial (transverse) magnetic field with respect to the laser propagation direction. Recently, there has been interest in filters realized with arbitrary-angle magnetic fields, which have been made by rotating permanent magnets with respect to the k-vector of the interrogating laser beam. However, the magnetic field angle achievable with this method is limited as field uniformity across the cell decreases as the rotation angle increases. In this work, we propose and demonstrate a new method of generating an arbitrary-angle magnetic field, using a solenoid to produce a small, and easily alterable, axial field, in conjunction with fixed permanent magnets to produce a large transverse field. We directly measure the fields produced by both methods, finding them to be very similar over the length of the vapor cell. We then compare the transmission profiles of filters produced using both methods, again finding excellent agreement. Finally, we demonstrate the sensitivity of the filter profile to changing magnetic field angle (solenoid current), which becomes easier to exploit with the much improved angle control and precision offered by our new design.

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Fine-structure changing collisions in ⁸⁷Rb upon D₂ excitation in the hyperfine Paschen-Back regime

Higgins,

Pizzey,

Hughes

2024

J. Phys. B: At. Mol. Opt. Phys.

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We investigate fine structure changing collisions in 87Rb vapour upon D2 excitation in a thermal vapour at 75°C; the atoms are placed in a 0.6 T axial magnetic field in order to gain access to the hyperfine Pashen-Back regime. Following optical excitation on the D2 line, the exothermic transfer 5P3/2 →5P1/2 occurs as a consequence of buffer-gas collisions; the 87Rb subsequently emits a photon on the D1 transition. We employ single-photon counting apparatus to monitor the D1 fluorescence, with an etalon filter to provide high spectral resolution. By studying the D1 fluorescence when the D2 excitation laser is scanned, we see that during the collisional transfer process the m′J quantum number of the atom changes, but the nuclear spin projection quantum number, m′I , is conserved. A simple kinematic model incorporating a coefficient of restitution in the collision accounted for the change in velocity distribution of atoms undergoing collisions, and the resulting fluorescence lineshape. The experiment is conducted with a nominally “buffer-gas free” vapour cell; our results show that fine structure changing collisions are important with such media, and point out possible implications for quantum-optics experiments in thermal vapours producing entangled photon pairs with the double ladder configuration, and solar physics magneto-optical filters.

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Voigt transmission windows in optically thick atomic vapours: a method to create single-peaked line centre filters

Cited by 3 publications

References 75 publications

Indirect measurement of atomic magneto-optical rotation via Hilbert transform

Indirect measurement of atomic magneto-optical rotation via Hilbert transform

A device for magnetic-field angle control in magneto-optical filters using a solenoid-permanent magnet pair

Fine-structure changing collisions in ⁸⁷Rb upon D₂ excitation in the hyperfine Paschen-Back regime

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Voigt transmission windows in optically thick atomic vapours: a method to create single-peaked line centre filters

Cited by 3 publications

References 75 publications

Indirect measurement of atomic magneto-optical rotation via Hilbert transform

Indirect measurement of atomic magneto-optical rotation via Hilbert transform

A device for magnetic-field angle control in magneto-optical filters using a solenoid-permanent magnet pair

Fine-structure changing collisions in 87Rb upon D2 excitation in the hyperfine Paschen-Back regime

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Product

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Fine-structure changing collisions in ⁸⁷Rb upon D₂ excitation in the hyperfine Paschen-Back regime