Faraday effect of light caused by plane gravitational wave

TL;DR

This paper investigates how weak plane gravitational waves induce a rotation in the polarization plane of linearly polarized light, revealing dependencies on wave amplitude, wavelength, and propagation direction.

Contribution

It provides a detailed analysis of the gravitational Faraday effect caused by weak plane GWs, including effects of different polarisation modes and ellipticity.

Findings

Rotation proportional to wave amplitude and squared distance

Maximum rotation occurs when light propagates perpendicular to GW

No rotation when light and GW propagate in same or opposite directions

Abstract

Gravitational field can cause a rotation of polarisation plane of light. This phenomenon is known as the gravitational Faraday effect. We study the gravitational Faraday effect of linearly polarised light propagating in the gravitational field of a weak plane gravitational wave (GW) with $+$, $\times$, and elliptical polarisation modes. The corresponding gravitational Faraday rotation is proportional to the wave amplitude and to the squared distance traveled by light and it is inversely proportional to the GW's squared wavelength. The rotation is also maximal if light propagates in the direction perpendicular to the GW propagation, along directions of its polarisation. There is no gravitational Faraday rotation when light and the GW propagate in the same or opposite directions, or it propagates along directions perpendicular to directions of the GW polarisation. Helicity of elliptically polarised GW gives higher-order contribution to the gravitational Faraday rotation.