Abstract
The optical interaction of light and matter is modeled as an oscillating dipole in a plane wave electromagnetic field. We analyze absorption, scattering and extinction for this system by the energy flow, visualized as streamlines of the Poynting vector. Depending on the dissipative damping of the oscillator, a part of the streamlines ends up in the dipole. Based on a graphical investigation of the streamlines, this represents the absorption cross section, and forms a far-field absorption aperture. In the near-field of the oscillator, a modification of the aperture is observed. As in the case for a linear dipole, we model the energy flow and derive the effective absorption apertures for an oscillator with a circular dipole characteristics – such as an atom in free space.
Highlights
One of the most fundamental processes which involves the interaction of light and matter is the attenuation of light by a nanoscopic emitter
The incident plane wave has no constant phase on the surface of a half sphere, the integral depends on the radius and on how many wave peaks and valleys are collected
The shape, we found for the absorption cross section of a Hertzian dipole is equivalent to the results of Ref.[30]
Summary
The optical interaction of light and matter is modeled as an oscillating dipole in a plane wave electromagnetic field. The paper is organized as follows: In section 2 the basic effect of light extinction and absorption is reviewed It starts with a perfect dipole, introduces the polarizability and the loss-channels. The incident plane wave has no constant phase on the surface of a half sphere, the integral depends on the radius and on how many wave peaks and valleys are collected Both extinction terms together add up to the amount of the scattered power in all 4π steradians. We assume the emitter is coupled to both the vacuum (which causes scattering and radiation reaction, but no extraction of power from the electromagnetic field), and to other bath(s) that can dephase the dipole response. We only consider the case of the absorption cross-section, such that a certain loss, e.g. a transfer to heat, is introduced by the emitter. A more general description can be found using Eqn 8 σext
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