Orbital angular momentum modes of high-gain parametric down-conversion

TL;DR

This paper explores the properties of orbital angular momentum modes in high-gain parametric down-conversion, demonstrating control over the OAM spectrum through pump power and source configuration, with potential applications in quantum information and imaging.

Contribution

It provides the first detailed study of OAM mode content in high-gain PDC and shows how to manipulate it via experimental parameters.

Findings

OAM mode content can be controlled by pump power.

The source configuration influences the OAM spectrum.

High-gain PDC exhibits correlated photon numbers in OAM modes.

Abstract

Light beams with orbital angular momentum (OAM) are convenient carriers of quantum information. They can be also used for imparting rotational motion to particles and provide high resolution in imaging. Due to the conservation of OAM in parametric down-conversion (PDC), signal and idler photons generated at low gain have perfectly anti-correlated OAM values. It is interesting to study the OAM properties of high-gain PDC, where the same OAM modes can be populated with large, but correlated, numbers of photons. Here we investigate the OAM spectrum of high-gain PDC and show that the OAM mode content can be controlled by varying the pump power and the configuration of the source. In our experiment, we use a source consisting of two nonlinear crystals separated by an air gap. We discuss the OAM properties of PDC radiation emitted by this source and suggest possible modifications.