Abstract The absorption, dispersion and transmission are controlled and modified with the intensities of Laguerre–Gaussian control fields in a four level cesium atomic medium. The normal and anomalous slope of dispersion are investigated for subluminal and superluminal propagation. The maximum measured value of positive/negative group index is n g =±1×107, at which, the group velocity is ±30 ms−1. The maximum delay time between the two beams at the detector without dragging is 0.414 ns and in the presence of dragging is measured to 0.44 ns. The fractional change in delay time without and in the presence of dragging Δt F is measured to ±2%. The maximum phase shift without dragging is reported to 2.6 micro radian and in the presence of dragging is investigated to ±4 micro radian. The fractional change in phase shift is reported from −200% to 50% and may be used for gravitational waves detection and other signals identification.
Abstract The absorption, dispersion and transmission are controlled and modified with the intensities of Laguerre–Gaussian control fields in a four level cesium atomic medium. The normal and anomalous slope of dispersion are investigated for subluminal and superluminal propagation. The maximum measured value of positive/negative group index is n g =±1×107, at which, the group velocity is ±30 ms−1. The maximum delay time between the two beams at the detector without dragging is 0.414 ns and in the presence of dragging is measured to 0.44 ns. The fractional change in delay time without and in the presence of dragging Δt F is measured to ±2%. The maximum phase shift without dragging is reported to 2.6 micro radian and in the presence of dragging is investigated to ±4 micro radian. The fractional change in phase shift is reported from −200% to 50% and may be used for gravitational waves detection and other signals identification.
Abstract We used a theoretical approach to study and investigate that how light pulses move faster than light in a four level atomic medium. In this study Laguerre-Gaussian (LG) beam waist, represented by F and strength Z is controlled. We examine the localized absorption and dispersion characteristics inside the four level atomic medium, illustrating that altering the beam waist affects the group velocity. According to the findings that we obtained, the group velocity at lower beam waists is between -0.0004c to -0.0002c, and the group index is negative, ranging from -0.0015 to -0.0005 respectively. As the pulse waist expands the extent of localized absorption and dispersion widens, yet the superluminal performance stays unchanged. Potentially useful in fields such as gravitational wave detection, soliton radar systems, and high-speed optical computing, this study sheds fresh information on the adaptability of light propagation in dispersive surfaces.
We studied and investigated whether light pulses travel faster then light in a four-level atomic medium using a theoretical method. Laguerre-Gaussian (LG) beam waist, denoted by F and strength Z, is regulated in this investigation. We analyses the localized absorption and dispersion properties within the four level atomic medium as well as demonstrate how the group velocity is affected by changing the beam waist. Our results showed that the team index remained negative, with values spanning -0.0015 to -0.0005, and the speed of the group at reduced beam-like waists was among -0.0004 and -0.0002 c. While the superluminal capability remains constant, the level of localized absorption as well as dispersion increases with the pulse waist. This work provides new insights into the flexibility of light propagation on dispersive surfaces, which may be helpful in domains like gravitational wave motion detection methods, soliton scanning systems, and high-frequency optical computation.
We studied and investigated whether light pulses travel faster then light in a four-level atomic medium using a theoretical method. Laguerre-Gaussian (LG) beam waist, denoted by F and strength Z, is regulated in this investigation. We analyses the localized absorption and dispersion properties within the four level atomic medium as well as demonstrate how the group velocity is affected by changing the beam waist. Our results showed that the team index remained negative, with values spanning -0.0015 to -0.0005, and the speed of the group at reduced beam-like waists was among -0.0004 and -0.0002 c. While the superluminal capability remains constant, the level of localized absorption as well as dispersion increases with the pulse waist. This work provides new insights into the flexibility of light propagation on dispersive surfaces, which may be helpful in domains like gravitational wave motion detection methods, soliton scanning systems, and high-frequency optical computation.
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.
We studied and investigated whether light pulses travel faster then light in a four-level atomic medium using a theoretical method. Laguerre-Gaussian (LG) beam waist, denoted by F and strength Z, is regulated in this investigation. We analyses the localized absorption and dispersion properties within the four level atomic medium as well as demonstrate how the group velocity is affected by changing the beam waist. Our results showed that the team index remained negative, with values spanning -0.0015 to -0.0005, and the speed of the group at reduced beam-like waists was among -0.0004 and -0.0002 c. While the superluminal capability remains constant, the level of localized absorption as well as dispersion increases with the pulse waist. This work provides new insights into the flexibility of light propagation on dispersive surfaces, which may be helpful in domains like gravitational wave motion detection methods, soliton scanning systems, and high-frequency optical computation.
We studied and investigated whether light pulses travel faster then light in a four-level atomic medium using a theoretical method. Laguerre-Gaussian (LG) beam waist, denoted by F and strength Z, is regulated in this investigation. We analyses the localized absorption and dispersion properties within the four level atomic medium as well as demonstrate how the group velocity is affected by changing the beam waist. Our results showed that the team index remained negative, with values spanning -0.0015 to -0.0005, and the speed of the group at reduced beam-like waists was among -0.0004 and -0.0002 c. While the superluminal capability remains constant, the level of localized absorption as well as dispersion increases with the pulse waist. This work provides new insights into the flexibility of light propagation on dispersive surfaces, which may be helpful in domains like gravitational wave motion detection methods, soliton scanning systems, and high-frequency optical computation.