Light scattering by an oscillating dipole in a focused beam

TL;DR

This paper investigates how a focused beam interacts with a single oscillating dipole, analyzing power ratios, phase changes, and comparing different theoretical approaches for precise understanding.

Contribution

It introduces a detailed analysis of light scattering by a dipole in a focused beam, comparing Debye diffraction integrals and multipole expansion methods.

Findings

The scattered to incident power ratio depends on the oscillator's cross section and focal area.

Debye diffraction and multipole expansion methods are shown to be equivalent.

Phase shifts of the electric field upon interaction are characterized.

Abstract

The interaction between a focused beam and a single classical oscillating dipole or a two-level system located at the focal spot is investigated. In particular, the ratio of the scattered to incident power is studied in terms of the oscillator's scattering cross section and the effective focal area. Debye diffraction integrals are applied to calculate it and results are reported for a directional dipolar wave. Multipole expansion of the incident beam is then considered and the equivalence between this and the Debye diffraction approach is discussed. Finally, the phase change of the electric field upon the interaction with a single oscillator is studied.