Interference Generation of a Reverse Energy Flow with Varying Orbital and Spin Angular Momentum Density

Abstract

This paper presents a novel method for generating and shaping reverse energy flow through the interference of light fields from a minimal number of point light sources. Until now, reverse energy flow has only been observed using complex light fields, such as optical vortices or cylindrical vector beams, limiting the formation of reverse energy flow near the optical axis. We demonstrate both analytically and numerically that unbounded regions of reverse energy flow can be achieved with just two point light sources, positioned asymmetrically at specific angles (e.g., 90 or 45 degrees) and with particular polarization states. The results indicate that the relative reverse energy flow can be enhanced by increasing the number of sources to three or four, adjusting their polarization, or introducing a vortex phase singularity. The presence of an initially embedded asymmetry in the fields under consideration leads to the formation of a non-uniform distribution of spin and orbital angular momentum density. Variations in the polarization state, as well as the introduction of a vortex phase singularity, allow for changing the distribution of angular momentum density while maintaining the presence of a reverse energy flow. We also explore the feasibility of implementing the obtained results using sectional phase diffractive optical elements, which will enhance the energy efficiency of the generated fields compared to point sources.

Keywords

• energy flow
• angular momentum
• polarization
• multi-beam interference
• Richards–Wolf formulas