Optical Angular Momentum Manipulations in a Four Wave Mixing Process

TL;DR

This paper explores how four-wave mixing in a double-{ extLambda} setup can manipulate optical orbital angular momentum (OAM), revealing conservation laws, independence of intensity squeezing from OAM, and new OAM transfer techniques with composite vortices.

Contribution

It demonstrates OAM conservation in four-wave mixing, shows intensity squeezing is unaffected by OAM, and introduces methods for OAM transfer using composite vortex pump fields.

Findings

OAM of the Stokes field obeys conservation law.

Maximum intensity squeezing is independent of OAM.

Composite vortices enable transfer of total topological charge.

Abstract

We investigate the spatial and quantum intensity correlations between the probe and Stokes optical fields produced via four-wave mixing in a double-{\Lambda} configuration, when both incoming probe and control fields carry non-zero optical orbital angular momentum (OAM). We observed that the topological charge of the generated Stokes field obeyed the OAM conservation law. However, the maximum values and optimal conditions for the intensity squeezing between the probe and Stokes fields were largely independent of the angular momenta of the beams, even when these two fields had significantly different OAM charges. We also investigated the case of a composite-vortex pump field, containing two closely-positioned optical vortices, and showed that the generated Stokes field carried the OAM corresponding to the total topological charge of the pump field, further expanding the range of possible OAM manipulation techniques.