The complex Maxwell stress tensor theorem: The imaginary stress tensor and the reactive strength of orbital momentum. A novel scenery underlying electromagnetic and optical forces

TL;DR

This paper introduces a new theoretical framework involving the imaginary part of the Maxwell stress tensor and reactive orbital momentum, revealing a universal reactive phenomenon that influences optical forces and can improve optical manipulation efficiency.

Contribution

It presents the complex Maxwell stress tensor theorem and the concept of reactive strength of orbital momentum, expanding the understanding of electromagnetic forces in classical electrodynamics.

Findings

Discovery of a universal reactive phenomenon affecting optical forces.

Introduction of the imaginary Lorentz force and reactive orbital momentum.

Potential to enhance optical manipulation efficiency without increasing power.

Abstract

We uncover the existence of a universal phenomenon concerning the electromagnetic optical force exerted by light or other electromagnetic waves on a distribution of charges and currents in general, and of particles in particular. This conveys the appearence of underlying reactive quantities that hinder radiation pressure and currently observed time-averaged forces. This constitutes a novel paradigm of the mechanical efficiency of light on matter, and completes the landscape of the electromagnetic force in classical electrodynamics; widening our understanding in the design of both illumination and particles in optical manipulation without the need of increasing the illuminating power, and thus lowering dissipation and heating. We show that this may be accomplished through the minimization of what we establish as the reactive strength of canonical (i.e. orbital) momentum, which plays against the optical force a role analogous to that of the reactive power versus the radiation efficiency of an antenna. This long time overlooked quantity, important for current progress of optical manipulation, and that stems from the complex Maxwell theorem of conservation of complex momentum that we put forward, as well as its alternating flow associated to the imaginary part of the complex Maxwell stress tensor, conform the imaginary Lorentz force that we introduce in this work, and that like the reactive strength of orbital momentum, is antagonic to the well-known time-averaged force; thus making this reactive Lorentz force indirectly observable near wavelengths at which the time-averaged force is lowered.