The gravitational field of a laser beam beyond the short wavelength approximation

TL;DR

This paper explores the gravitational effects of laser beams with finite wavelengths, revealing novel phenomena like frame-dragging and beam deflection, which deepen understanding of light's gravitational properties beyond the short wavelength approximation.

Contribution

It introduces a detailed model of laser beam gravity considering diffraction and finite wavelengths, highlighting effects not captured by previous short wavelength approximations.

Findings

Frame-dragging caused by laser beam spin angular momentum.

Deflection of co-propagating test beams overlapping with the source.

Effects are currently too small for experimental detection.

Abstract

Light carries energy, and therefore, it is the source of a gravitational field. The gravitational field of a beam of light in the short wavelength approximation has been studied by several authors. In this article, we consider light of finite wavelengths by describing a laser beam as a solution of Maxwell's equations and taking diffraction into account. Then, novel features of the gravitational field of a laser beam become apparent, such as frame-dragging due to its spin angular momentum and the deflection of parallel co-propagating test beams that overlap with the source beam. Even though the effects are too small to be detected with current technology, they are of conceptual interest, revealing the gravitational properties of light.