We study by computation and experiment an electromagnetically induced absorption resonance in the Hanle configuration with a transverse magnetic field on a closed Fg → Fe = Fg+1 transition with co-propagating orthogonal circularly polarized probe and coupling optical fields. At high coupling field intensities, the Hanle resonance changes sign due to a shift in atomic population from Zeeman sublevels associated with a probe field cyclic transition to sublevels associated with a coupling field cyclic transition at zero magnetic field. We also show that a similar sign reversal does not occur for π-polarized and σ-polarized coupling fields. © 2010 IOP Publishing Ltd.

M. Pattabiraman

Department Of Physics

Nibedita Ram

ATOMIC POPULATION

Circularly polarized

COUPLING FIELDS

CYCLIC TRANSITIONS

ELECTROMAGNETICALLY INDUCED ABSORPTION

OPTICAL FIELD

PROBE FIELD

Sign reversal

TRANSVERSE MAGNETIC FIELD

ZEEMAN SUBLEVELS

ZERO MAGNETIC FIELDS

Absorption

Magnetic fields

Resonance

Probes

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IIT Madras

Sign reversal of Hanle electromagnetically induced absorption with orthogonal circularly polarized optical fields

Journal of Physics B: Atomic, Molecular and Optical Physics

The influence of the closed Fg = 2 → Fe = 3 transition on the neighboring Fg = 2 → Fe = 1 and Fg = 2 → Fe = 2 open transitions of the 87Rb D2 line, partially resolved under Doppler broadening, is studied at different ellipticities in the Hanle configuration with longitudinal and transverse magnetic field scans. We show that a sign reversal from an electromagnetically induced transparency (EIT) resonance to an electromagnetically induced absorption (EIA) resonance occurs with an increase in ellipticity for the Fg = 2 → Fe = 1 transition in a transverse field scan. This transformation is not observed for a longitudinal field scan. These observations are attributed to the higher amplitude of the EIA resonance for the Fg = 2 → Fe = 3 transition in transverse field scans for elliptical polarized light. The EIA character in the Hanle transmission profile of Fg = 2 → Fe = 1 and Fg = 2 → Fe = 2 transitions is enhanced (weakened) when the laser beam frequency is detuned towards (away from) the Fg = 2 → Fe = 3 transition. We show by computation that at higher ellipticities, a transformation from an EIT to an EIA resonance for the Fg = 2 → Fe = 2 transition occurs at low frequency shifts (towards the Fg = 2 → Fe = 3 transition) in a transverse field scan.

Hanle electromagnetically induced absorption in open

We computationally compare Hanle-type resonances for a Fg=1 → Fe=0 transition of the 87RbD2line for magnetic field scans parallel (longitudinal scan) and perpendicular (transverse scan) to the direction of propagation of the optical field in the presence of an additional transverse magnetic field (TMF). For a linearly polarized light, the coherent population trapping (CPT) resonances split at line centre and are identical for both longitudinal and transverse scans. When the probe beam ellipticity is varied, the effect of the TMF is found to be opposite for longitudinal and transverse scans. For a longitudinal scan, the splitting observed in the CPT resonance evolves into an enhanced absorption resonance with an increase in ellipticity. For a transverse scan, the splitting vanishes at higher ellipticities. This can be understood in terms of population redistribution in the ground state sublevels and near-neighbor ground state coherences created by the TMF. We also show that the enhanced absorption signal that splits the CPT resonance strongly depends on transit time, and the CPT resonance strength depends on the excited state dephasing rate. © 2014 IOP Publishing Ltd.

Effect of an additional magnetic field on Hanle-type absorption resonances

Investigation of coherent absorption resonance via electromagnetically induced absorption (EIA) spectra in rubidium vapour has been done in presence of a repumping laser and an external magnetic field. The EIA line shape gets enhanced and symmetric with the application of the repumping laser. In presence of an external magnetic field the amplitude of the EIA resonance gradually diminishes and at higher magnetic field, two absorption dip-like structures along with a transmission peak in between is obtained. Theoretically calculated spectra based on density matrix approach show a good agreement with the observations. © 2015 Elsevier B.V. All rights reserved.

Chemical Physics Letters

A study of the repumping laser and external magnetic field effect on coherent absorption resonance in alkali vapour

Physical Review A

Electromagnetically induced absorption in a bichromatic laser field

Absorption spectra for strong pump and probe in atomic beam of cesium atoms

Optics Communications

Coupling-probe laser spectroscopy of degenerate two-level systems: An experimental survey of various polarisation combinations

Optics Letters

Switching from “absorption within transparency” to “transparency within transparency” in an electromagnetically induced absorption dominated transition

Intensity dependence narrowing of electromagnetically induced absorption in a Doppler-broadened medium

Journal	Journal of Physics B: Atomic, Molecular and Optical Physics
ISSN	09534075
Open Access	No