The propagation of a Laguerre-Gaussian (LG) beam through a dispersive medium is investigated. The effect of the doughnut-like intensity profile of the probe LG beam on the group velocity is studied. We find an analytical expression for the group velocity out of the optical axis and compare with its projection onto the propagation axis. It is turned out that the group velocity vector is along the optical axis at the waist of the beam and the Rayleigh range. We numerically and analytically investigate the effect of the helical phase front of the coupling LG field on the group velocity of the probe LG field in a four-level double V-type quantum system. Our analysis predicts a strange behavior for the group velocity of the probe LG beam inside a normal dispersive medium in the gain region so that it can exceed the speed of light in free space, leads to the gain-assisted superluminal light propagation in normal dispersion. Such an unusual propagation of the LG beam results from the distortion of its helical phase front via the classical interference of the planar and LG fields. The obtained results may find some potential applications in increasing the velocity of the information transmission in optical communications.
The propagation of a Laguerre-Gaussian (LG) beam through a dispersive medium is investigated. The effect of the doughnut-like intensity profile of the probe LG beam on the group velocity is studied. We find an analytical expression for the group velocity out of the optical axis and compare with its projection onto the propagation axis. It is turned out that the group velocity vector is along the optical axis at the waist of the beam and the Rayleigh range. We numerically and analytically investigate the effect of the helical phase front of the coupling LG field on the group velocity of the probe LG field in a four-level double V-type quantum system. Our analysis predicts a strange behavior for the group velocity of the probe LG beam inside a normal dispersive medium in the gain region so that it can exceed the speed of light in free space, leads to the gain-assisted superluminal light propagation in normal dispersion. Such an unusual propagation of the LG beam results from the distortion of its helical phase front via the classical interference of the planar and LG fields. The obtained results may find some potential applications in increasing the velocity of the information transmission in optical communications.
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.
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.
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.