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

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.

Rotation of polarization in the gravitational field of a laser beam—Faraday effect and optical activity

“…This is in contrast to gravitational photon-photon scattering in perturbative quantum gravity discussed in [45]. In [5], we showed that the gravitational field of a laser beam considered as a proper perturbative solution of Maxwell's equations beyond the short wavelength approximation does depend on the helicity of the laser beam. In the present article, we showed that, accordingly, the polarizations of two light beams couple gravitationally; two circularly polarized light beams inflict on each other a phase shift depending on the relation between their he-licity.…”

“…In this section, we summarize the description of the laser beam and its gravitational field presented in [5]. A laser beam is accurately described by a Gaussian beam.…”

“…This is gravitational spin-spin coupling of light (see [46] for a general review on gravitational spin-spin coupling). Together with frame-dragging and the deflection of a parallel co-propagating test ray discussed in [5], the gravitational Faraday effect and gravitational optical activity are only visible when the source is treated beyond geometric ray optics. It can be expected that orbital angular momentum of light would contribute to the effects mentioned above (see [4] for an investigation of the gravitational field of light beams with orbital angular momentum).…”

Influence of gravitational waves upon light. Part I. Null geodesics, radar distance and frequency shift

“…Last, we emphasize that the metric (2.2) is a solution of the Einstein's field equations in vacuum, so another possible aspect of the interaction between GWs and electromagnetic waves, namely, the effect of light energy-momentum tensor as a source to the curvature of spacetime will not be considered in this work, that is, light will be held as a test field only (cf. [21]).…”

Influence of gravitational waves upon light in the Minkowski background: from null geodesics to interferometry

“…Last, we emphasize that the metric ( 4) is a solution of the Einstein's field equations in vacuum, so another possible aspect of the interaction between GWs and electromagnetic waves, namely, the effect of light energymomentum tensor as a source to the curvature of spacetime will not be considered in this work, that is, light will be held as a test field only (cf. [27]).…”