Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1405.3053 · Physical Review A

Uniform phase modulation via control of refractive index in a thermal atom vapor with vanishing diffraction or absorption

Lida Zhang, Jörg Evers

Published Aug 14, 2014• 13 citations
arXivHTMLPDF

Abstract

A scheme is proposed to achieve substantial controllable phase modulation for a probe field propagating through a thermal atomic vapor in double-$\ensuremath{\Lambda}$ configuration. The phase modulation is based on manipulating the linear susceptibility of the probe field, paraxial diffraction is eliminated by exploiting the thermal motion of atoms, and residual absorption is compensated via an incoherent pump field. As a result of the homogeneous change in the refractive index, a strong controllable uniform phase modulation without paraxial diffraction is achieved essentially independent of the spatial profile or the intensity of the probe field. This phase shift can be controlled via the intensities of the control or the incoherent pump fields. A possible proof-of-principle experiment in alkali-metal atoms is discussed.

DOI
10.1103/physreva.90.023826

Related papers

Refractive Index Enhancement with Vanishing Absorption in an Atomic Vapor

Nicholas Proite, Brett Unks, Jonathan Tyler Green +1 more

We report a proof-of-principle experiment where the refractive index of an atomic vapor is enhanced while maintaining vanishing absorption of the beam. The key idea is to drive alkali atoms in a vapor with appropriate control lasers and induce a gain resonance and an absorption resonance for a probe beam in a two-photon Raman configuration. The strength and the position of these two resonances can be manipulated by changing the parameters of the control lasers. By using the interference between these two resonances, we obtain an enhanced refractive index without an increase in the absorption.

arXiv:0807.2584•Physical Review Letters•Sep 29, 2008•70 citations

Diffractionless image propagation and frequency conversion via four-wave mixing exploiting the thermal motion of atoms

Lida Zhang, Jörg Evers

A setup to frequency-convert an arbitrary image encoded in the spatial profile of a probe field onto a signal field using four-wave mixing in a thermal atom vapor is proposed. The atomic motion is exploited to cancel diffraction of both signal and probe fields simultaneously. We show that an incoherent probe field can be used to enhance the transverse momentum bandwidth which can be propagated without diffraction, such that smaller structures with higher spatial resolution can be transmitted. It furthermore compensates linear absorption with nonlinear gain, to improve the four-wave mixing performance since the propagation dynamics of the various field intensities is favorably modified.

arXiv:1309.0615•Physical Review A•Jan 15, 2014•13 citations

Kerr-field-induced tunable optical atomic waveguide

Sandeep Sharma, Tarak Nath Dey

We propose an efficient scheme for the generation of tunable optical waveguides based on atomic vapor in an $N$-type configuration. We exploit both control-field-induced transparency and Kerr-field-induced absorption to produce a flexible probe transparency window otherwise not feasible. We employ a suitable spatial profile of control and Kerr beams to create a high contrast refractive index modulation that holds the key to guiding a weak narrow probe beam. Further, we numerically demonstrate that high-contrast tunable waveguide permits the propagation of different modes of probe beam to several Rayleigh lengths without diffraction. This efficient guiding of narrow optical beam may have important applications in large-density image processing and high-resolution imaging.

arXiv:1709.08408•Physical Review A•Nov 6, 2017•6 citations

Control of beam propagation in optically written waveguides beyond the paraxial approximation

Lida Zhang, Tarak Nath Dey, Jörg Evers

Beam propagation beyond the paraxial approximation is studied in an optically written waveguide structure. The waveguide structure, which leads to diffractionless light propagation, is imprinted on a medium consisting of a five-level atomic vapor driven by an incoherent pump and two coherent spatially dependent control and plane-wave fields. We first study beam propagation in a single optically written waveguide and find that the paraxial approximation does not provide an accurate description of the probe propagation. We then employ coherent control fields such that two parallel and one tilted Gaussian beams produce a branched waveguide structure. The tilted beam allows selective steering of the probe beam into different branches of the waveguide structure. The transmission of the probe beam for a particular branch can be improved by changing the width of the titled Gaussian control beam as well as the intensity of the spatially dependent incoherent pump field.

arXiv:1303.1376•Physical Review A•Apr 30, 2013•20 citations

Nondiffracting optical beams in a three-level Raman system

Tarak Nath Dey, Jörg Evers

Diffractionless propagation of optical beams through atomic vapors is investigated. The atoms in the vapor are operated in a three-level Raman configuration. A suitably chosen control beam couples to one of the transitions, and thereby creates a spatially varying index of refraction modulation in the warm atomic vapor for a probe beam that couples to the other transition in the atoms. We show that a Laguerre-Gaussian control beam allows the propagation of single Gaussian probe field modes as well as multi-Gaussian modes and non-Gaussian modes over macroscopic distances without diffraction. This opens perspectives for the propagation of arbitrary images through warm atomic vapors.

arXiv:1108.1875•Physical Review A•Oct 24, 2011•27 citations

P T Symmetry with a System of Three-Level Atoms

Chao Hang, Guoxiang Huang, V. V. Konotop

We show that a vapor of multilevel atoms driven by far-off-resonant laser beams, with the possibility of interference of two Raman resonances, is highly efficient for creating parity-time symmetric profiles of the probe-field refractive index, whose real part is symmetric and imaginary part is antisymmetric in space. The spatial modulation of the probe-field susceptibility is achieved by a proper combination of standing-wave strong control fields and of Stark shifts induced by far-off-resonance laser fields. As particular examples we explore a mixture of isotopes of rubidium atoms and design a parity-time symmetric lattice and a parabolic refractive index with a linear imaginary part.

arXiv:1212.5486•Physical Review Letters•Feb 21, 2013•276 citations
A scheme is proposed to achieve substantial controllable phase modulation for a probe field propagating through a thermal atomic vapor in double-\ensuremathΛ\ensuremath{\Lambda}\ensuremathΛ configuration. The phase modulation is based on manipulating the linear susceptibility of the probe field, paraxial diffraction is eliminated by exploiting the thermal motion of atoms, and residual absorption is compensated via an incoherent pump field. As a result of the homogeneous change in the refractive index, a strong controllable uniform phase modulation without paraxial diffraction is achieved essentially independent of the spatial profile or the intensity of the probe field. This phase shift can be controlled via the intensities of the control or the incoherent pump fields. A possible proof-of-principle experiment in alkali-metal atoms is discussed.
We report a proof-of-principle experiment where the refractive index of an atomic vapor is enhanced while maintaining vanishing absorption of the beam. The key idea is to drive alkali atoms in a vapor with appropriate control lasers and induce a gain resonance and an absorption resonance for a probe beam in a two-photon Raman configuration. The strength and the position of these two resonances can be manipulated by changing the parameters of the control lasers. By using the interference between these two resonances, we obtain an enhanced refractive index without an increase in the absorption.
A setup to frequency-convert an arbitrary image encoded in the spatial profile of a probe field onto a signal field using four-wave mixing in a thermal atom vapor is proposed. The atomic motion is exploited to cancel diffraction of both signal and probe fields simultaneously. We show that an incoherent probe field can be used to enhance the transverse momentum bandwidth which can be propagated without diffraction, such that smaller structures with higher spatial resolution can be transmitted. It furthermore compensates linear absorption with nonlinear gain, to improve the four-wave mixing performance since the propagation dynamics of the various field intensities is favorably modified.
We propose an efficient scheme for the generation of tunable optical waveguides based on atomic vapor in an NNN-type configuration. We exploit both control-field-induced transparency and Kerr-field-induced absorption to produce a flexible probe transparency window otherwise not feasible. We employ a suitable spatial profile of control and Kerr beams to create a high contrast refractive index modulation that holds the key to guiding a weak narrow probe beam. Further, we numerically demonstrate that high-contrast tunable waveguide permits the propagation of different modes of probe beam to several Rayleigh lengths without diffraction. This efficient guiding of narrow optical beam may have important applications in large-density image processing and high-resolution imaging.
Beam propagation beyond the paraxial approximation is studied in an optically written waveguide structure. The waveguide structure, which leads to diffractionless light propagation, is imprinted on a medium consisting of a five-level atomic vapor driven by an incoherent pump and two coherent spatially dependent control and plane-wave fields. We first study beam propagation in a single optically written waveguide and find that the paraxial approximation does not provide an accurate description of the probe propagation. We then employ coherent control fields such that two parallel and one tilted Gaussian beams produce a branched waveguide structure. The tilted beam allows selective steering of the probe beam into different branches of the waveguide structure. The transmission of the probe beam for a particular branch can be improved by changing the width of the titled Gaussian control beam as well as the intensity of the spatially dependent incoherent pump field.
Diffractionless propagation of optical beams through atomic vapors is investigated. The atoms in the vapor are operated in a three-level Raman configuration. A suitably chosen control beam couples to one of the transitions, and thereby creates a spatially varying index of refraction modulation in the warm atomic vapor for a probe beam that couples to the other transition in the atoms. We show that a Laguerre-Gaussian control beam allows the propagation of single Gaussian probe field modes as well as multi-Gaussian modes and non-Gaussian modes over macroscopic distances without diffraction. This opens perspectives for the propagation of arbitrary images through warm atomic vapors.
We show that a vapor of multilevel atoms driven by far-off-resonant laser beams, with the possibility of interference of two Raman resonances, is highly efficient for creating parity-time symmetric profiles of the probe-field refractive index, whose real part is symmetric and imaginary part is antisymmetric in space. The spatial modulation of the probe-field susceptibility is achieved by a proper combination of standing-wave strong control fields and of Stark shifts induced by far-off-resonance laser fields. As particular examples we explore a mixture of isotopes of rubidium atoms and design a parity-time symmetric lattice and a parabolic refractive index with a linear imaginary part.