Anisotropy in scattering of light from an atom into the guided modes of a nanofiber

TL;DR

This paper investigates how a multilevel cesium atom scatters guided light in a nanofiber, revealing asymmetric scattering rates influenced by atomic structure and light polarization, which could impact nanophotonic applications.

Contribution

It demonstrates the anisotropic scattering of guided light from a multilevel atom in a nanofiber, highlighting the role of atomic structure and polarization in scattering asymmetry.

Findings

Scattering rates are asymmetric between forward and backward directions.

Asymmetry depends on the polarization of the probe field.

Two-level atom case shows similar asymmetry due to complex dipole vectors.

Abstract

We study the scattering of guided light from a multilevel cesium atom with the transitions between the hyperfine levels $6S_{1/2}F=4$ and $6P_{3/2}F'=5$ of the $D_2$ line into the guided modes of a nanofiber. We show that the rate of scattering of guided light from the atom in the steady-state regime into the guided modes is asymmetric with respect to the forward and backward directions and depends on the polarization of the probe field. The asymmetry between the forward and backward scattering is a result of the complex transition structure of the atom and the existence of a longitudinal component of the guided-mode profile function. In the case of a two-level atom, the rates of spontaneous emission (and consequently the rates of scattering) into the forward and backward guided modes differ from each other when the atomic dipole matrix-element vector is a complex vector in the plane that contains the fiber axis and the atomic position.