圆棒介质波导的电磁波传播特性

通过简单的数学分析,推导圆棒介质波导的导模传播条件及特征方程,讨论电磁波在圆棒介质波导中的传播特性。     

Near-field effect in a superthin film of resonance atoms

A boundary-value problem of nonlinear resonance optics in the interaction of intense light with a superthin film of two-level atoms is solved. In solving this boundary-value problem, the authors draw on the idea of a discrete-continuous system in which the atoms are distributed in a discrete manner in the vicinity of the point of observation. It is shown that detailed account of the dipole field leads to a near-field effect both inside the film and outside it in the near zone with respect to outer film surfaces. Various properties of the near-field effect in stationary irradiation of the film with quasi-resonance radiation with allowance for a resonance shift are investigated. It is shown, in particular, that, in the near zone, there is a nonexponential dependence of the fields of reflected and transmitted waves on the coordinate of the point of observation. Ul'yanovsk State University, 42, L. Tolstoi St., Ul'yanovsk, 432700, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 236–246, March–April, 1998.     

The most general form of the vector potential in electrodynamics

The most general form of the vector potential is deduced in curved spacetime using general relativity. It is shown that the longitudinal and timelike components of the vector potential exist in general and are richly structured. Electromagnetic energy from the vacuum is given by the quaternion valued canonical energy-momentum. It is argued that a dipole intercepts such energy and uses it for the generation of electromotive force. Whittaker’sU(l) decomposition of the scalar potential applied to the potential between the poles of a dipole, shows that the dipole continuously receives electromagnetic energy from the complex plane and emits it in real space. The known broken 3-symmetry of the dipole results in a relaxation from 3-flow symmetry to 4-flow symmetry. Considered with its clustering virtual charges of opposite sign, an isolated charge becomes a set of composite dipoles, each having a potential between its poles that, inU(1) electrodynamics, is composed of the Whittaker structure and dynamics. Thus the source charge continuously emits energy in all directions in 3-space while obeying 4-space energy conservation. This resolves the long-vexing problem of the association of the “source” charge and its fields and potentials. In initiating 4-flow symmetry while breaking 3-flow symmetry, the charge, as a set of dipoles, initiates a reordering of a fraction of the surrounding vacuum energy, with the reordering spreading in all directions at the speed of light and involving canonical determinism between time currents and spacial energy currents. This constitutes a giant, spreading negentropy which continues as long as the dipole (or charge) is intact. Some implications of this previously unsuspected giant negentropy are pointed out for the Poynting energy flow theory, and as to how electrical circuits and loads are powered.     

Resonant coupling in the van der Waals interaction between an excited alkali atom and a dielectric surface: an experimental study via stepwise selective reflection spectroscopy

We present a detailed experimental study of the evaluation of the van der Waals (vW) atom-surface interaction for high-lying excited states of alkali-metal atoms (Cs and Rb), notably when they couple resonantly with a surface-polariton mode of the neighbouring dielectric surface. This report extends our initial observation [Phys. Rev. Lett. 83, 5467 (1999)] of a vW repulsion between Cs(6D_3/2) and a sapphire surface. The experiment is based upon FM selective reflection spectroscopy, on a transition reaching a high-lying state from a resonance level, that has been thermally pumped by an initial one-photon step. Along with a strong vW repulsion fitted with a blue lineshift, -160±25 kHz μm³ for Cs(6D_3/2) in front of a sapphire surface (with a perpendicular c-axis), we demonstrate a weaker vW repulsion (-32±5 kHz μm³) for Cs(6D_3/2) in front of a YAG surface, as due to a similar resonant coupling at 12 μm between a virtual atomic emission (6D_3/2-7P_1/2) and the surface polariton modes. A resonant behaviour of Rb(6D_5/2) in front of a sapphire surface exists also because of analogous decay channels in the 12 μm range. Finally, one demonstrates that fused silica, nonresonant for a virtual transition in the 12 μm range and hence weakly attracting for Cs(6D_3/2), exhibits a resonant behaviour for Cs(9S_1/2) as due to its surface polariton resonance in the 8-9 μm range. The limiting factors that affect both the accuracy of the theoretical prediction, and that of the fitting method applied to the experimental data, are discussed in the conclusion. Received 16 January 2003 / Received in final form 25 March 2003 Published online 5 May 2003