Self-bound droplets of light with orbital angular momentum

TL;DR

This paper demonstrates the formation of optical self-bound droplets with orbital angular momentum in a photon fluid within a nonlinear medium, exhibiting liquid-like properties due to competing long-range interactions.

Contribution

It introduces the concept of light droplets with orbital angular momentum, formed through competing interactions in a photon fluid, expanding the understanding of optical matter analogues.

Findings

Optical droplets with liquid-like properties are formed in a photon fluid.

Droplets carry orbital angular momentum and are stabilized by competing interactions.

These droplets exhibit bulk pressure and compressibility similar to matter droplets.

Abstract

Systems with competing attractive and repulsive interactions have a tendency to condense into droplets. This is the case for water in a sink, liquid helium and dipolar atomic gases. Here, we consider a photon fluid which is formed in the transverse plane of a monochromatic laser beam propagating in an attractive (focusing) nonlocal nonlinear medium. In this setting we demonstrate the formation of the optical analogue of matter wave droplets, and study their properties. The system we consider admits droplets that carry orbital angular momentum. We find bound states possessing liquid-like properties, such as bulk pressure and compressibility. Interestingly, these droplets of light, as opposed to optical vortices, form due to the competition between long-range s-wave (monopole) and d-wave (quadrupole) interactions as well as diffraction.