Optical solitons in curved spacetime

TL;DR

This paper investigates how weak gravitational fields influence optical solitons in nonlinear media, deriving a modified Schrödinger equation that accounts for spacetime curvature effects, with a focus on optical fibers in Schwarzschild spacetime.

Contribution

It introduces a new theoretical framework combining general relativity and nonlinear optics to describe soliton propagation in curved spacetime environments.

Findings

Gravitational fields modify the propagation of optical solitons.

Mechanical deformations dominate in radial fiber orientations in Schwarzschild spacetime.

Derived a non-linear Schrödinger equation incorporating spacetime curvature effects.

Abstract

Light propagation in curved spacetime is at the basis of some of the most stringent tests of Einstein's general relativity. At the same time, light propagation in media is at the basis of several communication systems. Given the ubiquity of the gravitational field, and the exquisite level of sensitivity of optical measurements, the time is ripe for investigations combining these two aspects and studying light propagation in media located in curved spacetime. In this work, we focus on the effect of a weak gravitational field on the propagation of optical solitons in non-linear optical media. We derive a non-linear Schr\"{o}dinger equation describing the propagation of an optical pulse in an effective, gradient-index medium in flat spacetime, encoding both the material properties and curved spacetime effects. In analyzing the special case of propagation in a 1D optical fiber, we also include the effect of mechanical deformations and show it to be the dominant effect for a fiber oriented in the radial direction in Schwarzschild spacetime.