Shaping the evanescent field of optical nanofibers for cold atom trapping

TL;DR

This paper explores how to shape the evanescent field of optical nanofibers using specific mode combinations to create versatile trapping geometries for cold atoms, including spirals and lattices.

Contribution

It introduces a method to manipulate evanescent fields by combining fundamental and higher-order modes to form customizable trapping potentials.

Findings

Formation of four-spiral trapping potentials using mode combinations

Transformation of spiral into lattice configurations by polarization control

Analysis of mode excitation effects on trapping geometries

Abstract

We investigate trapping geometries for cold, neutral atoms that can be created in the evanescent field of a tapered optical fibre by combining the fundamental mode with one of the next lowest possible modes, namely the HE21 mode. Counter propagating red-detuned HE21 modes are combined with a blue-detuned HE11 fundamental mode to form a potential in the shape of four intertwined spirals. By changing the polar- ization from circular to linear in each of the two counter-propagating HE21 modes simultaneously the 4-helix configuration can be transformed into a lattice configuration. The modification to the 4-helix configuration due to unwanted excitation of the the T E01 and T M01 modes is also discussed.