Superluminal propagation of light is a well-established phenomenon and has motivated immense research interest that has led to state-of-the-art knowledge and potential applications in the emerging technology of quantum optics and photonics. This study presents a theoretical analysis of the gain-assisted superluminal light propagation in a four-level $N$-type atomic system by exploiting the scheme of electromagnetically induced gain and superluminal propagation of surface plasmon polaritons (SPPs) along the gain-assisted atomic-metal interface simultaneously. In addition, a theoretical demonstration is presented on the comparison between Fresnel's rotary photon drag and SPP drag in view of light polarization state rotation by rotating the coherent atomic medium and the atomic-metal interface, respectively. Analogous to photon drag in the superluminal anomalous dispersion region where light polarization rotation occurs opposite the rotation of the gain-assisted atomic medium, the rotation of the atomic-metal interface also rotates the polarization state of SPPs opposite the rotation of the interface. This further confirms the superluminal nature of SPPs propagating along the interface with negative group velocity. Rabi frequencies of the control and pump fields considerably modify both photon and SPP drag coefficients. Metal conductivity also controls SPP propagation.
Superluminal propagation of light is a well-established phenomenon and has motivated immense research interest that has led to state-of-the-art knowledge and potential applications in the emerging technology of quantum optics and photonics. This study presents a theoretical analysis of the gain-assisted superluminal light propagation in a four-level N-type atomic system by exploiting the scheme of electromagnetically induced gain and superluminal propagation of surface plasmon polaritons (SPPs) along the gain-assisted atomic-metal interface simultaneously. In addition, a theoretical demonstration is presented on the comparison between Fresnel's rotary photon drag and SPP drag in view of light polarization state rotation by rotating the coherent atomic medium and the atomic-metal interface, respectively. Analogous to photon drag in the superluminal anomalous dispersion region where light polarization rotation occurs opposite the rotation of the gain-assisted atomic medium, the rotation of the atomic-metal interface also rotates the polarization state of SPPs opposite the rotation of the interface. This further confirms the superluminal nature of SPPs propagating along the interface with negative group velocity. Rabi frequencies of the control and pump fields considerably modify both photon and SPP drag coefficients. Metal conductivity also controls SPP propagation.
Abstract Motivated by the need for controllable fast-light platforms in compact photonic systems, this work investigates surface plasmon polariton (SPP)-assisted superluminal group propagation in a four-level cesium atomic medium driven by Laguerre-Gaussian control fields. The aim is to examine how the beam waist and intensity of the structured control fields, together with plasmonic field confinement, modify absorption, dispersion, group index, and group velocity. Using a density-matrix formulation, the probe-field coherence is obtained, the optical susceptibility is calculated, and the group velocity is evaluated from the dispersion slope while the SPP contribution is included through the effective dielectric response. The results show that increasing the Laguerre-Gaussian beam waist broadens the spatial region of anomalous dispersion and negative group index, while SPP confinement strengthens the local atom-field interaction and enhances susceptibility modulation. The study demonstrates a tunable route for controlling localized superluminal group propagation without implying superluminal information transfer, with potential applications in optical switching, photonic signal processing, plasmonic sensing, and quantum optical devices.
Hereby, we amend several spectral parameters reported in our earlier work [N. Khan et al., Phys. Rev. A 96, 013848 (2017); Phys. Rev. A 96, 049906(E) (2017)], which led to unphysical predictions to be tested experimentally. In particular, the resulting probe wavelength was in the decimeter band, as pointed out in a Comment by Macke and S\'egard [B. Macke and B. S\'egard, preceding Comment, Phys. Rev. A 99, 057801 (2019)]. After incorporating the corrected parameters, the predictions of our theoretical demonstration on the gain-assisted superluminal propagation and rotary drag of photon and that of surface plasmon polaritons are improved to a good degree of accuracy and expected to be tested realistically. In particular, even the minimum values of rotary drag for both photon and surface plasmon polaritons are on the order of few microradians, thus falling within the range of experimental testability.
Abstract We investigate magneto-optical rotation (MOR) of surface plasmon polaritons (SPPs) at the interface of a metal and a four-level atomic system. The MOR of SPPs can be controlled and modified with the intensity and frequency of the applied fields. We show the birefringence enhancement of the weak probe fields propagating through the atomic medium in the presence of the static magnetic field. The external magnetic field has a vital role in the generation and control over the MOR of SPPs. The MOR completely stops when either the external magnetic field or the probe field or both are tuned to resonance. A pretty behavior of MOR of SPPs is observed for a specific set of control field frequency. The enhanced MOR of SPP has significant applications in atomic spectroscopy, optical communication, nano-photonics, optical switches, and precise measurement.
Abstract We theoretically investigate the spectral hole burning of surface plasmon polaritons (SPPs) at an interface between rubidium ( 87 Rb) atomic medium and silver. A typical Lamb dip can be observed at a certain frequency where the absorption of SPPs is suddenly reduced. By applying Kerr-type nonlinearity to the 87 Rb atomic gas, the slope of dispersion becomes more normal and steeper. Under the effect of Doppler broadening, a group index of at the SPPs hole burning region is obtained and is further enhanced to with the application of Kerr-nonlinearity. Similarly, the propagation length of SPPs is increased at the hole burning region and is further enhanced with Kerr-nonlinearity. Further, we show that this nonlinear effect results in the enhancement of the phase shift from 0.02 to 1.5 radian at the hole burning region. These results may find important applications in nano-photonics, optical tweezers, photovoltaic devices and sensing technology.
Abstract Controlling the basic properties of light such as polarization, angular momentum, and speed through various optical media leads to interesting phenomena in various fields such as quantum optics, photonics, plasmonics, and quantum information technology. Few of the phenomenon include, for instance, light storage, ultra-slow and ultra-fast propagation, optical transparency, and quantum entanglement via quantum coherence or superposition. The understanding of these phenomenon of milestone implications paved the way for the invention of novel classical and quantum technology. In this article, we present detailed theoretical and numerical demonstration on the dispersion-dependent phenomenon of slow and fast light, optically induced transparency, and photon drag. For this, we employ a three-level scheme of an ensemble of GaAs\AlGaAs double quantum dot molecule in cascade configuration. In particular, by tuning the medium dispersion we predict interesting interplay between ultra-slow and ultra-fast light propagation with vanishing, infinite, ultra-positive and ultra-negative group velocities, and optical-assisted quantum transparency. The quantum coherence of the dressed states modifies considerably the optical properties of the system in view of dispersion, absorption, electron energy loss, transmission, and photon drag. An interesting interplay between ultra-slow to ultra-fast propagation is found by tuning various optical parameters. The calculated superluminal value of group velocity is ± 6 × 1 0 11 m s −1 . We also predict light propagation at vanishing and infinite group velocity. The calculated light drag is ± 6 × 10 − 6 rad/m.