Optical vortices of slow light using tripod scheme

We consider propagation, storing and retrieval of slow light (probe beam) in a resonant atomic medium illuminated by two control laser beams of larger intensity.The probe and two control beams act on atoms in a tripod configuration of light-matter coupling.The first control beam is allowed to have an orbital angular momentum (OAM).Application of the second vortex-free control laser ensures the adiabatic (lossless) propagation of the probe beam at the vortex core where the intensity of the first control laser goes to zero.Storing and release of the probe beam is accomplished by switching off and on the control laser beams leading to the transfer of the optical vortex from the first control beam to the regenerated probe field.A part of the stored probe beam remains frozen in the medium in the form of atomic spin excitations, the number of which increases with increasing intensity of the second control laser.We analyze such losses in the regenerated probe beam and provide conditions for the optical vortex of the control beam to be transferred efficiently to the restored probe beam.We consider propagation, storing and retrieval of slow light (probe beam) in a resonant atomic medium illuminated by two control laser beams of larger intensity.The probe and two control beams act on atoms in a tripod configuration of light-matter coupling.The first control beam is allowed to have an orbital angular momentum (OAM).Application of the second vortex-free control laser ensures the adiabatic (lossless) propagation of the probe beam at the vortex core where the intensity of the first control laser goes to zero.Storing and release of the probe beam is accomplished by switching off and on the control laser beams leading to the transfer of the optical vortex from the first control beam to the regenerated probe field.A part of the stored probe beam remains frozen in the medium in the form of atomic spin excitations, the number of which increases with increasing intensity of the second control laser.We analyze such losses in the regenerated probe beam and provide conditions for the optical vortex of the control beam to be transferred efficiently to the restored probe beam.

arXiv:1104.5536Journal of OpticsApr 27, 201132 citations

Slow polaritons with orbital angular momentum in atomic gases

Julius Ruseckas, Algirdas Mekys, Gediminas Juzeliūnas

Polariton formalism is applied for studying the propagation of a probe field of light in a cloud of cold atoms influenced by two control laser beams of larger intensity. The laser beams couple resonantly three hyperfine atomic ground states to a common excited state, thus forming a tripod configuration of the atomic energy levels involved. The first control beam can have an optical vortex, with the intensity of the beam going to zero at the vortex core. The second control beam without a vortex ensures the lossless (adiabatic) propagation of the probe beam at a vortex core of the first control laser. We investigate the storage of the probe pulse into atomic coherences by switching off the control beams and its subsequent retrieval by switching the control beams on. The optical vortex is transferred from the control to the probe fields during the storage or retrieval of the probe field. We analyze the conditions needed for the vortex to be transferred efficiently to the regenerated probe beam and discuss the possibilities of experimental implementation of the proposed scheme using atoms such as rubidium or sodium.Polariton formalism is applied for studying the propagation of a probe field of light in a cloud of cold atoms influenced by two control laser beams of larger intensity. The laser beams couple resonantly three hyperfine atomic ground states to a common excited state, thus forming a tripod configuration of the atomic energy levels involved. The first control beam can have an optical vortex, with the intensity of the beam going to zero at the vortex core. The second control beam without a vortex ensures the lossless (adiabatic) propagation of the probe beam at a vortex core of the first control laser. We investigate the storage of the probe pulse into atomic coherences by switching off the control beams and its subsequent retrieval by switching the control beams on. The optical vortex is transferred from the control to the probe fields during the storage or retrieval of the probe field. We analyze the conditions needed for the vortex to be transferred efficiently to the regenerated probe beam and discuss the possibilities of experimental implementation of the proposed scheme using atoms such as rubidium or sodium.

arXiv:1102.4321Physical Review AFeb 17, 201161 citations

Manipulation of slow light with orbital angular momentum in cold atomic gases

Julius Ruseckas, Algirdas Mekys, Gediminas Juzeliūnas

We study the propagation of a weak pulse of slow light in a cloud of cold atoms controlled by two additional laser beams of larger intensity in a tripod configuration of the light-matter coupling. We consider a case where one of the control beams has an optical vortex and thus has a zero intensity at the center. The presence of the second control beams restores adiabaticity in the propagation of the probe beam. This makes it possible to exchange the optical vortex between the control and probe fields during the storage. We analyze conditions for the vortex of the control beam to be transferred efficiently to the restored probe beam.We study the propagation of a weak pulse of slow light in a cloud of cold atoms controlled by two additional laser beams of larger intensity in a tripod configuration of the light-matter coupling. We consider a case where one of the control beams has an optical vortex and thus has a zero intensity at the center. The presence of the second control beams restores adiabaticity in the propagation of the probe beam. This makes it possible to exchange the optical vortex between the control and probe fields during the storage. We analyze conditions for the vortex of the control beam to be transferred efficiently to the restored probe beam.

Optics and SpectroscopyMar 1, 20105 citations

Transfer of orbital angular momentum of light using two-component slow light

Julius Ruseckas, Viačeslav Kudriašov, Ite A. Yu +1 more

We study the manipulation of slow light with an orbital angular momentum propagating in a cloud of cold atoms. Atoms are affected by four co-propagating control laser beams in a double tripod configuration of the atomic energy levels involved, allowing us to minimize the losses at the vortex core of the control beams. In such a situation the atomic medium is transparent for a pair of co-propagating probe fields, leading to the creation of two-component (spinor) slow light. We study the interaction between the probe fields when two control beams carry optical vortices of opposite helicity. As a result, a transfer of the optical vortex takes place from the control to the probe fields without switching off and on the control beams. This feature is missing in a single tripod scheme where the optical vortex can be transferred from the control to the probe field only during either the storage or retrieval of light.We study the manipulation of slow light with an orbital angular momentum propagating in a cloud of cold atoms. Atoms are affected by four co-propagating control laser beams in a double tripod configuration of the atomic energy levels involved, allowing us to minimize the losses at the vortex core of the control beams. In such a situation the atomic medium is transparent for a pair of co-propagating probe fields, leading to the creation of two-component (spinor) slow light. We study the interaction between the probe fields when two control beams carry optical vortices of opposite helicity. As a result, a transfer of the optical vortex takes place from the control to the probe fields without switching off and on the control beams. This feature is missing in a single tripod scheme where the optical vortex can be transferred from the control to the probe field only during either the storage or retrieval of light.

arXiv:1306.1709Physical Review AMay 28, 201387 citations

Matched optical vortices of slow light using a tripod coherently prepared scheme

Hamid Reza Hamedi, Ite A. Yu, Emmanuel Paspalakis

This paper explores the propagation of optical vortices of slow light inside a four-level tripod atomic light-matter coupling system. Initially, the system is prepared in a coherent superposition of two out of the three lower levels by, for example, coherent population trapping, while the third lower state remains unoccupied. The unoccupied state is coupled to a strong control laser field with a constant Rabi frequency, lacking orbital angular momentum (OAM). Simultaneously, one of the remaining lower states interacts with a weak vortex beam. The third lower state has no initial coupling to any field. This arrangement effectively closes the level transitions, resulting in a phase-dependent configuration. By solving the Maxwell-Schr\"odinger equations, we provide analytical evidence that the application of a strong control field can generate an additional optical vortex of slow light. This vortex possesses the same OAM as the incident vortex beam. Furthermore, we explore the matching of optical vortices at different propagation distances, contingent upon the intensity of the control field. Additionally, our analysis extends to a more complex five-level tripod and $\mathrm{\ensuremath{\Lambda}}$ scheme, where we introduce two additional strong control fields to prepare the atoms in a coherent superposition of two lower levels.This paper explores the propagation of optical vortices of slow light inside a four-level tripod atomic light-matter coupling system. Initially, the system is prepared in a coherent superposition of two out of the three lower levels by, for example, coherent population trapping, while the third lower state remains unoccupied. The unoccupied state is coupled to a strong control laser field with a constant Rabi frequency, lacking orbital angular momentum (OAM). Simultaneously, one of the remaining lower states interacts with a weak vortex beam. The third lower state has no initial coupling to any field. This arrangement effectively closes the level transitions, resulting in a phase-dependent configuration. By solving the Maxwell-Schr\"odinger equations, we provide analytical evidence that the application of a strong control field can generate an additional optical vortex of slow light. This vortex possesses the same OAM as the incident vortex beam. Furthermore, we explore the matching of optical vortices at different propagation distances, contingent upon the intensity of the control field. Additionally, our analysis extends to a more complex five-level tripod and $\mathrm{\ensuremath{\Lambda}}$ scheme, where we introduce two additional strong control fields to prepare the atoms in a coherent superposition of two lower levels.

Physical Review ANov 30, 202310 citations

Transfer of optical vortices in coherently prepared media

Hamid Reza Hamedi, Julius Ruseckas, Emmanuel Paspalakis +1 more

We consider transfer of optical vortices between laser pulses carrying orbital angular momentum in a cloud of cold atoms characterized by the $\mathrm{\ensuremath{\Lambda}}$ configuration of the atom-light coupling. The atoms are initially prepared in a coherent superposition of the lower levels, creating a so-called phaseonium medium. If a single vortex beam initially acts on one transition of the scheme, an extra laser beam is subsequently generated with the same vorticity as that of the incident vortex beam. The absorption of the incident probe beam takes place mostly at the beginning of the atomic medium within the absorption length. The losses disappear as the probe beam propagates deeper into the medium where the atoms are transferred to their dark states. The method is extended to a tripod atom-light coupling scheme and a more general ( $n+1$ )-level scheme containing $n$ ground states and one excited state, allowing for creation of multiple twisted light beams. We also analyze generation of composite optical vortices in the scheme using a superposition of two initial vortex beams and study lossless propagation of such composite vortices.We consider transfer of optical vortices between laser pulses carrying orbital angular momentum in a cloud of cold atoms characterized by the $\mathrm{\ensuremath{\Lambda}}$ configuration of the atom-light coupling. The atoms are initially prepared in a coherent superposition of the lower levels, creating a so-called phaseonium medium. If a single vortex beam initially acts on one transition of the scheme, an extra laser beam is subsequently generated with the same vorticity as that of the incident vortex beam. The absorption of the incident probe beam takes place mostly at the beginning of the atomic medium within the absorption length. The losses disappear as the probe beam propagates deeper into the medium where the atoms are transferred to their dark states. The method is extended to a tripod atom-light coupling scheme and a more general ($n+1$)-level scheme containing $n$ ground states and one excited state, allowing for creation of multiple twisted light beams. We also analyze generation of composite optical vortices in the scheme using a superposition of two initial vortex beams and study lossless propagation of such composite vortices.

arXiv:1811.10647Physical Review AMar 6, 201980 citations

n+1

)-level scheme containing

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ground states and one excited state, allowing for creation of multiple twisted light beams. We also analyze generation of composite optical vortices in the scheme using a superposition of two initial vortex beams and study lossless propagation of such composite vortices.