Abstract We derive a formula for computing the resonance energy transfer (RET) rate between two two-level atoms—one in the excited state (donor) and the other in the ground state (acceptor)—oriented along the axial direction near a finite-length dielectric cylinder, which can be regarded as a finite optical fiber. By employing a truncated Born expansion of the homogeneous Green’s tensor and using numerical solutions, we identify a range of parameters for which the finite cylinder can be well approximated by an infinite one, whose Green’s tensor is known in closed form. Beyond the validity of the infinite-cylinder approximation, we find that the effect of the fiber tip on the RET rate becomes significant, particularly when the donor–acceptor pair is located above the top edge of the fiber.
Abstract We derive a formula for computing the resonance energy transfer (RET) rate between two two-level atoms—one in the excited state (donor) and the other in the ground state (acceptor)—oriented along the axial direction near a finite-length dielectric cylinder, which can be regarded as a finite optical fiber. By employing a truncated Born expansion of the homogeneous Green’s tensor and using numerical solutions, we identify a range of parameters for which the finite cylinder can be well approximated by an infinite one, whose Green’s tensor is known in closed form. Beyond the validity of the infinite-cylinder approximation, we find that the effect of the fiber tip on the RET rate becomes significant, particularly when the donor–acceptor pair is located above the top edge of the fiber.
Abstract The resonance energy transfer rate between an excited atom and a ground-state one depends on various factors such as the matching between the donor and acceptor wavelengths, location of the atoms, and the environment that surrounds them. We investigate the interatomic resonance energy transfer rate in the presence of a cylindrical dielectric multi-layer structure using the Green’s tensor formalism. The permittivities of the layers are interchanged periodically between low and high values, so as to create a photonic band-gap system in the radial direction. We present results for atoms situated in a cross section normal to the cylinder axis. The contrast between low and high permittivities is varied to elucidate the effect of the band-gap structure. Furthermore, the results are compared with those for atoms located near a perfectly reflecting c-ylinder.
Abstract Using the Green’s function approach, we investigate the resonance energy transfer (RET) rate between two parallel, identical two-level atoms in the presence of three types of cylindrical system: a distributed Bragg reflector (DBR), a perfectly reflecting wall (PRW), and a two-layer silicon fiber. Our analysis, incorporating the cut-off frequency condition, reveals significant suppression of the RET rate for atoms positioned along the axis of the cylinder with the PRW. In contrast, for atoms located within the DBR, the RET rate is enhanced in the far zone. Additionally, we find that for atoms oriented radially are placed inside or near the surface of the silicon fiber, the RET rate is entirely inhibited. We also investigate the Casimir–Polder (CP) interaction between a cut-off-frequency DBR and an excited atom, discovering a fully attractive potential towards the surface for the atom within the waveguide.
Abstract We consider how the rate of resonance energy transfer (RET) between an excited atom and a ground-state one is affected by the presence of a cylindrical photonic band-gap waveguide by using the Green’s function approach. Both positions inside and outside the wall and three types of atomic dipole moment orientations, namely radial, azimuthal and axial orientations, are examined. Results for the photonic band-gap structure and those for the perfectly reflecting one are compared. Differences between the two are found to be significant near the surfaces. Frequency dependence of the rate, which is beyond the perfectly reflecting wall model, is investigated. It is shown that when the waveguide is located in between two atoms which have transition dipole moments parallel with the axis and transition frequency falling within the gap region, the RET is suppressed.
We study the force of light on a two-level atom near an ultrathin optical fiber using the mode function method and the Green tensor technique. We show that the total force consists of the driving-field force, the spontaneous-emission recoil force, and the fiber-induced van der Waals potential force. Due to the existence of a nonzero axial component of the field in a guided mode, the Rabi frequency and, hence, the magnitude of the force of the guided driving field may depend on the propagation direction. When the atomic dipole rotates in the meridional plane, the spontaneous-emission recoil force may arise as a result of the asymmetric spontaneous emission with respect to opposite propagation directions. The van der Waals potential for the atom in the ground state is off-resonant and opposite to the off-resonant part of the van der Waals potential for the atom in the excited state. Unlike the potential for the ground state, the potential for the excited state may oscillate depending on the distance from the atom to the fiber surface.
We study the force of light on a two-level atom near an ultrathin optical fiber using the mode function method and the Green tensor technique. We show that the total force consists of the driving-field force, the spontaneous-emission recoil force, and the fiber-induced van der Waals potential force. Due to the existence of a nonzero axial component of the field in a guided mode, the Rabi frequency and, hence, the magnitude of the force of the guided driving field may depend on the propagation direction. When the atomic dipole rotates in the meridional plane, the spontaneous-emission recoil force may arise as a result of the asymmetric spontaneous emission with respect to opposite propagation directions. The van der Waals potential for the atom in the ground state is off-resonant and opposite to the off-resonant part of the van der Waals potential for the atom in the excited state. Unlike the potential for the ground state, the potential for the excited state may oscillate depending on the distance from the atom to the fiber surface.
We consider the energy transfer process between two identical atoms placed inside a perfectly conducting cylindrical waveguide. We first introduce a general analytical expression of the energy transfer amplitude in terms of the electromagnetic Green's tensor; we then evaluate it in the case of a cylindrical waveguide made of a perfect conductor, for which analytical expressions of the Green's tensor exist. We numerically analyze the energy transfer amplitude when the radius of the waveguide is such that the transition frequency of both atoms is below the lower cutoff frequency of the waveguide, so that the resonant photon exchange is strongly suppressed. We consider both cases of atomic dipoles parallel and orthogonal to the axis of the guide. In both cases, we find that the energy transfer is modified by the presence of the waveguide. In the near zone, that is when the atomic separation is smaller than the atomic transition wavelength, the change, with respect to the free-space case, is small for axial dipoles, while it is larger for radial dipoles; it grows when the intermediate region between near and far zone is approached. In the far zone, we find that the energy transfer amplitude is strongly suppressed by the waveguide, becoming virtually zero. A physical interpretation of these results is discussed. Finally, we discuss the resonance interaction energy and force between two identical correlated atoms in the waveguide, one excited and the other in the ground state, prepared in their symmetric or antisymmetric superposition.