Observation of microscale nonparaxial optical bottle beams

TL;DR

This paper predicts and demonstrates microscale nonparaxial optical bottle beams with high contrast and controllable shapes, achieved through caustic surface engineering, enabling precise three-dimensional light confinement at the microscale.

Contribution

It introduces a method to generate and control microscale nonparaxial optical bottle beams using caustic surface design, with analytical phase profiles for practical implementation.

Findings

Successful experimental observation of microscale nonparaxial optical bottle beams.

Analytical expressions for phase profiles in real and Fourier space.

High contrast and controllable 3D light confinement achieved.

Abstract

We predict and experimentally observe three-dimensional microscale nonparaxial optical bottle beams based on the generation of a caustic surface under revolution. Such bottle beams exhibit high contrast between the surrounding surface and the effectively void interior. Via caustic engineering we can precisely control the functional form of the high intensity surface to achieve microscale bottle beams with longitudinal and transverse dimensions of the same order of magnitude. Although, in general, the phase profile at the input plane can be computed numerically, we find closed form expressions for bottle beams with various type of surfaces both in real and in the Fourier space.