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Steep dispersion and coherent control of Faraday rotation in a potassium vapor cell

Andreas Lampis, Robert Culver, Balázs Megyeri, J. Goldwin

Published Sep 29, 2015• 0 citations
OpenAlex

Abstract

Electromagnetically induced transparency (EIT) was studied in a heated vapor cell of potassium without buffer gas or anti-relaxation coating. Transparency windows 60 times narrower than the natural line width and group indices exceeding 6000 were generated using a simple optical setup with a single free-running laser and an acousto-optic modulator. A longitudinal magnetic field was used to split the EIT feature into three components for either lin$\perp$lin or lin$\parallel$lin polarizations of probe and coupling beams. Measurements of polarization rotation revealed that only the lin$\parallel$lin configuration leads to circular birefringence, an effect which we attribute to quantum interference between the multiple $\Lambda$-type subsystems contributing to the signal. The Verdet constant of the EIT medium was measured to be $(5.8\pm 0.3)\times 10^4$ rad/T/m, and a novel measurement of group index for circular polarization based on birefringence was demonstrated. For larger fields, where the individual peaks were well resolved, resonant polarization rotations of $(210\pm10)$ mrad/MHz were observed.

Related papers

Coherent control of group index and magneto-optical anisotropy in a multilevel atomic vapor

Andreas Lampis, Robert Culver, Balázs Megyeri +1 more

We study electromagnetically induced transparency (EIT) in a heated potassium vapor cell, using a simple optical setup with a single free-running diode laser and an acousto-optic modulator. Despite the fact that the Doppler width is comparable to the ground state hyperfine splitting, transparency windows with deeply sub-natural line widths and large group indices are obtained. A longitudinal magnetic field is used to split the EIT feature and induce magneto-optical anisotropy. Using the beat note between co-propagating coupling and probe beams, we perform a heterodyne measurement of the circular dichroism (and therefore birefringence) of the EIT medium. The observed spectra reveal that lin‖lin polarizations lead to greater anisotropy than lin⊥lin. A simplified ‖analytical model encompassing sixteen Zeeman states and eighteen Λ subsytems reproduces the experimental observations.

arXiv:1509.08776•Optics Express•Jun 29, 2016•20 citations

Electromagnetically Induced Transparency in Potassium Vapors: Features and Restrictions

Armen D. Sargsyan, P. A. Petrov, T. A. Vartanyan +1 more

Features of electromagnetically induced transparency (EIT) in potassium vapors at the D 1 line of the 39 K isotope are studied. EIT resonances with a subnatural width of 3.5 MHz have been recorded upon excitation by two independent narrow-band diode lasers in a 1-cm-long cell filled with a natural mixture of potassium isotopes and buffer gas. The splitting of EIT resonances in potassium vapors in longitudinal and transverse magnetic fields has been studied for the first time. The splitted components also have a subnatural width. The smallness of the coupling factor of the hyperfine structure in 39 K atoms leads to a transition to the Paschen—Back regime at relatively weaker magnetic fields than in the case of Cs, Rb, and Na atoms. Practical applications of the phenomena under study are noted. The theoretical model well explains the experiment.

Optics and Spectroscopy•Mar 1, 2016•10 citations

High Quality of Electromagnetically Induced Transparency Spectroscopy of 87Rb in a Buffer Gas Cell with Magnetic Field

Hong Cheng, Han-Mu Wang, Shan-Shan, Zhang +3 more

We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87Rb vapor with a buffer gas in a magnetic field at room temperature. It is found that the spectral lines caused by the velocity selective optical pump effects get much weaker and wider when the sample cell mixed with a 5-Torr N2 gas while the EIT signal kept almost unchanged. A weighted least-square fit is also developed to remove the Doppler broadening completely. This spectral method provides a way to measure the Zeeman splitting with high resolution, for example, the Λ-type EIT resonance splits into four peaks on the D2 line of 87Rb in the thermal 2-cm vapor cell with a magnetic field along the electric field of the linearly polarized coupling laser. The high resolution spectrum can be used to lock the laser to a given frequency by tuning the magnetic field.

arXiv:1703.02845•Mar 8, 2017•0 citations

Transformation of electromagnetically induced transparency into absorption in a thermal potassium optical cell with spin preserving coating

Silvia Gozzini, A. Lucchesini, C. Marinelli +4 more

We report a new experimental approach where an order of magnitude enhancement of the electromagnetically induced absorption (EIA) resonance contrast, thus making it similar to that of the EIT resonance contrast is observed under the same conditions. The EIA signal results from the interaction of a weak probe beam with a ground state that has been driven by the pump (counter-propagating) beam. Probe absorption spectra are presented where the laser frequency is slowly detuned over the D 1 line of 39 K vapor contained in a cell with a PDMS antirelaxation coating. In addition to the frequency detuning, a magnetic field orthogonal to the laser beams is scanned around zero value at a higher rate. With both laser beams linearly polarized, an EIT resonance is observed. However, changing the pump beam polarization from linear to circular reverses the resonance signal from EIT to EIA.

Journal of Physics Conference Series•Mar 1, 2016•2 citations

Electromagnetically induced transparency of 87 Rb in a buffer gas cell with magnetic field

Hong Cheng, Han-Mu Wang, Shanshan Zhang +3 more

Abstract We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87 Rb vapor at room temperature in a magnetic field with an arbitrary angle to the laser propagation direction. Rather than exposing atoms to a parallelled or transverse magnetic field as usual, in our work, we apply a magnetic field (up to 45 Gauss) with an arbitrary angle to the laser propagation direction and the spectra become much more complex. More EIT dips are observed due to the Zeeman splitting on the D 2 line of 87 Rb in a Λ -type configuration. With a 5 Torr N 2 buffer gas in the thermal 2 cm vapor cell, the state 5 2 P 3 / 2 has a very short effective lifetime, corresponding to a large energy broadening, which removes the velocity selective optical pumping effect almost completely and keeps the high resolution EIT spectrum for the energy splitting of 87 Rb in magnetic fields. The shifting of the EIT resonances with the strength of the applied magnetic field coincides well with the theory based on a full matrix Hamiltonian combined with a spectral decomposition method. Our work can be extended to measure the magnetic field vector in space. The effects of the detuning of the probe and coupling beams on the spectral lines are also investigated.

Journal of Physics B Atomic Molecular and Optical Physics•Apr 18, 2017•35 citations

Doppler narrowing, Zeeman and laser beam-shape effects in $Λ$-type Electromagnetically Induced Transparency on the $^{85}$Rb D2 line in a vapor cell

Lu Ma, Georg A. Raithel

We study $Λ$-type Electromagnetically Induced Transparency (EIT) on the Rb D2 transition in a buffer-gas-free thermal vapor cell without anti-relaxation coating. Experimental data show distinguished features of velocity-selective optical pumping and one EIT resonance. The Zeeman splitting of the EIT line in magnetic fields up to 12 Gauss is investigated. One Zeeman component is free of the first-order shift and its second-order shift agrees well with theory. The full width at half maximum (FWHM) of this magnetic-field-insensitive EIT resonance is reduced due to Doppler narrowing, scales linearly in Rabi frequency over the range studied, and reaches about 100~kHz at the lowest powers. These observations agree with an analytic model for a Doppler-broadened medium developed in Ref. \cite{PhysRevA.66.013805,7653385}. Numerical simulation using the Lindblad equation reveals that the transverse laser intensity distribution and two $Λ$-EIT systems must be included to fully account for the measured line width and line shape of the signals. Ground-state decoherence, caused by effects that include residual optical frequency fluctuations, atom-wall and trace-gas collisions, is discussed.

arXiv:2007.00495•Jul 1, 2020•0 citations
Electromagnetically induced transparency (EIT) was studied in a heated vapor cell of potassium without buffer gas or anti-relaxation coating. Transparency windows 60 times narrower than the natural line width and group indices exceeding 6000 were generated using a simple optical setup with a single free-running laser and an acousto-optic modulator. A longitudinal magnetic field was used to split the EIT feature into three components for either lin⊥\perp⊥lin or lin∥\parallel∥lin polarizations of probe and coupling beams. Measurements of polarization rotation revealed that only the lin∥\parallel∥lin configuration leads to circular birefringence, an effect which we attribute to quantum interference between the multiple Λ\LambdaΛ-type subsystems contributing to the signal. The Verdet constant of the EIT medium was measured to be (5.8±0.3)×104(5.8\pm 0.3)\times 10^4(5.8±0.3)×104 rad/T/m, and a novel measurement of group index for circular polarization based on birefringence was demonstrated. For larger fields, where the individual peaks were well resolved, resonant polarization rotations of (210±10)(210\pm10)(210±10) mrad/MHz were observed.
We study electromagnetically induced transparency (EIT) in a heated potassium vapor cell, using a simple optical setup with a single free-running diode laser and an acousto-optic modulator. Despite the fact that the Doppler width is comparable to the ground state hyperfine splitting, transparency windows with deeply sub-natural line widths and large group indices are obtained. A longitudinal magnetic field is used to split the EIT feature and induce magneto-optical anisotropy. Using the beat note between co-propagating coupling and probe beams, we perform a heterodyne measurement of the circular dichroism (and therefore birefringence) of the EIT medium. The observed spectra reveal that lin‖lin polarizations lead to greater anisotropy than lin⊥lin. A simplified ‖analytical model encompassing sixteen Zeeman states and eighteen Λ subsytems reproduces the experimental observations.
Features of electromagnetically induced transparency (EIT) in potassium vapors at the D 1 line of the 39 K isotope are studied. EIT resonances with a subnatural width of 3.5 MHz have been recorded upon excitation by two independent narrow-band diode lasers in a 1-cm-long cell filled with a natural mixture of potassium isotopes and buffer gas. The splitting of EIT resonances in potassium vapors in longitudinal and transverse magnetic fields has been studied for the first time. The splitted components also have a subnatural width. The smallness of the coupling factor of the hyperfine structure in 39 K atoms leads to a transition to the Paschen—Back regime at relatively weaker magnetic fields than in the case of Cs, Rb, and Na atoms. Practical applications of the phenomena under study are noted. The theoretical model well explains the experiment.
We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87Rb vapor with a buffer gas in a magnetic field at room temperature. It is found that the spectral lines caused by the velocity selective optical pump effects get much weaker and wider when the sample cell mixed with a 5-Torr N2 gas while the EIT signal kept almost unchanged. A weighted least-square fit is also developed to remove the Doppler broadening completely. This spectral method provides a way to measure the Zeeman splitting with high resolution, for example, the Λ-type EIT resonance splits into four peaks on the D2 line of 87Rb in the thermal 2-cm vapor cell with a magnetic field along the electric field of the linearly polarized coupling laser. The high resolution spectrum can be used to lock the laser to a given frequency by tuning the magnetic field.
We report a new experimental approach where an order of magnitude enhancement of the electromagnetically induced absorption (EIA) resonance contrast, thus making it similar to that of the EIT resonance contrast is observed under the same conditions. The EIA signal results from the interaction of a weak probe beam with a ground state that has been driven by the pump (counter-propagating) beam. Probe absorption spectra are presented where the laser frequency is slowly detuned over the D 1 line of 39 K vapor contained in a cell with a PDMS antirelaxation coating. In addition to the frequency detuning, a magnetic field orthogonal to the laser beams is scanned around zero value at a higher rate. With both laser beams linearly polarized, an EIT resonance is observed. However, changing the pump beam polarization from linear to circular reverses the resonance signal from EIT to EIA.
Abstract We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87 Rb vapor at room temperature in a magnetic field with an arbitrary angle to the laser propagation direction. Rather than exposing atoms to a parallelled or transverse magnetic field as usual, in our work, we apply a magnetic field (up to 45 Gauss) with an arbitrary angle to the laser propagation direction and the spectra become much more complex. More EIT dips are observed due to the Zeeman splitting on the D 2 line of 87 Rb in a Λ -type configuration. With a 5 Torr N 2 buffer gas in the thermal 2 cm vapor cell, the state 5 2 P 3 / 2 has a very short effective lifetime, corresponding to a large energy broadening, which removes the velocity selective optical pumping effect almost completely and keeps the high resolution EIT spectrum for the energy splitting of 87 Rb in magnetic fields. The shifting of the EIT resonances with the strength of the applied magnetic field coincides well with the theory based on a full matrix Hamiltonian combined with a spectral decomposition method. Our work can be extended to measure the magnetic field vector in space. The effects of the detuning of the probe and coupling beams on the spectral lines are also investigated.
Doppler narrowing, Zeeman and laser beam-shape effects in ΛΛΛ-type Electromagnetically Induced Transparency on the 85^{85}85Rb D2 line in a vapor cell
We study ΛΛΛ-type Electromagnetically Induced Transparency (EIT) on the Rb D2 transition in a buffer-gas-free thermal vapor cell without anti-relaxation coating. Experimental data show distinguished features of velocity-selective optical pumping and one EIT resonance. The Zeeman splitting of the EIT line in magnetic fields up to 12 Gauss is investigated. One Zeeman component is free of the first-order shift and its second-order shift agrees well with theory. The full width at half maximum (FWHM) of this magnetic-field-insensitive EIT resonance is reduced due to Doppler narrowing, scales linearly in Rabi frequency over the range studied, and reaches about 100~kHz at the lowest powers. These observations agree with an analytic model for a Doppler-broadened medium developed in Ref. \cite{PhysRevA.66.013805,7653385}. Numerical simulation using the Lindblad equation reveals that the transverse laser intensity distribution and two ΛΛΛ-EIT systems must be included to fully account for the measured line width and line shape of the signals. Ground-state decoherence, caused by effects that include residual optical frequency fluctuations, atom-wall and trace-gas collisions, is discussed.