arXiv:2101.07984 · Physical Review A

Resolving closely spaced levels for Doppler mismatched double resonance

Elijah Ogaro Nyakang’o, Kanhaiya Pandey

Published Jan 15, 2021• 9 citations

Abstract

In this paper, we present experimental techniques to resolve the closely spaced hyperfine levels of a weak transition by eliminating the residual or partial two-photon Doppler broadening and crossover resonances in a wavelength-mismatched double-resonance spectroscopy. The elimination of the partial Doppler broadening is based on velocity-induced population oscillation (VIPO) and velocity-selective saturation (VSS) effects followed by the subtraction of the broad background of the two-photon spectrum. Since the VIPO and VSS effects are the phenomena for near-zero-velocity group atoms, the subtraction gives rise to Doppler-free peaks and the closely spaced hyperfine levels of the $6{P}_{3/2}$ state in Rb are well resolved. The double-resonance experiment is conducted on the $5{S}_{1/2}\ensuremath{\rightarrow}5{P}_{3/2}$ strong transition (at 780 nm) and $5{S}_{1/2}\ensuremath{\rightarrow}6{P}_{3/2}$ weak transition (at 420 nm) at room temperature.

DOI: 10.1103/physreva.103.013107

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arXiv:2101.07984 · Physical Review A

Resolving closely spaced levels for Doppler mismatched double resonance

Elijah Ogaro Nyakang’o, Kanhaiya Pandey

Published Jan 15, 2021• 9 citations

arXiv HTML PDF

Abstract

6{P}_{3/2}

state in Rb are well resolved. The double-resonance experiment is conducted on the

5{S}_{1/2}\ensuremath{\rightarrow}5{P}_{3/2}

strong transition (at 780 nm) and

5{S}_{1/2}\ensuremath{\rightarrow}6{P}_{3/2}

weak transition (at 420 nm) at room temperature.

DOI: 10.1103/physreva.103.013107

Related papers

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Physical Review AFeb 1, 199861 citations

6{P}_{3/2}

state in Rb are well resolved. The double-resonance experiment is conducted on the

5{S}_{1/2}\ensuremath{\rightarrow}5{P}_{3/2}

strong transition (at 780 nm) and

5{S}_{1/2}\ensuremath{\rightarrow}6{P}_{3/2}

weak transition (at 420 nm) at room temperature.

5p_{3/2}

level which then decays by emission of

780

nm photons. Narrow dips appear in this otherwise broad

780

nm fluorescence, which allows resolution of the

6p_{3/2}

hyperfine structure. A rate equation model is used to interpret the spectra. It is also shown that these narrow peaks can be used to lock the frequency of the $420 $ nm laser. Using a second beam modulated in frequency produces three sets of spectra with known frequency spacings that can be used to perform an all-optical measurement of the hyperfine splittings of the $6p_{3/2} $ manifold in rubidium.

{\mathrm{D}}_{2}

) transitions. The counterpropagating pump and probe lasers are independently tunable in frequency, with the probe operating at the single-photon level. The two-dimensional spectrum measured as the laser frequencies are scanned shows fluorescence, Doppler-broadened absorption dips, and sub-Doppler features. The detuning between the pump and probe lasers allows compensation of the Doppler shift for all atomic velocities in the room-temperature vapor, meaning we observe sub-Doppler features for all atoms in the beam. We detail a theoretical model of the system that incorporates fluorescence, saturation effects, and optical pumping and compare this with the measured spectrum, finding a mean absolute percentage error of 3.11%. This high level of agreement allows us to extract the number density and temperature of the

\mathrm{Rb}

vapor from the two-dimensional spectrum. In the future this technique could be used as an atomic frequency standard for calibrating and characterising a single-photon or low-light-level source.

D_2

line of Rb. We then use an acousto-optic modulator (AOM) for frequency calibration to make precise hyperfine-interval measurements in the first excited

P_{3/2}

state of

^{85,87}

Rb and

^{133}

Cs.

{5S}_{1/2}

and the excited state

{6P}_{1/2}.

The coupling laser is employed on the linked transition ${5S}_{1/2}{\ensuremath{-}5P}_{3/2},$ inducing significant levels of transparency

(>70%)

nondissipatively and in the absence of optical pumping effects.