Nonlinear Faraday magneto-optic effects in a helically wound optical fiber

TL;DR

This paper investigates nonlinear Faraday magneto-optic effects in a helically wound optical fiber, revealing an intensity-dependent rotation angle due to nonlinear corrections, with derived analytic expressions and potential experimental implications.

Contribution

It introduces a theoretical framework for nonlinear Faraday effects in helically wound fibers, including analytic formulas accounting for nonlinear corrections to the Verdet constant and fiber torsion.

Findings

Identified an additional rotation angle proportional to optical intensity.

Derived analytic expressions for Faraday rotation in nonlinear regime.

Discussed potential experimental observations and implications.

Abstract

We thoroughly investigate the Faraday magneto-optical effects in a helically wound nonlinear optical fiber. We find the emergence of an additional rotation angle proportional to the optical intensity, arised from the nonlinear corrections to both the Verdet constant and the fiber torsion. By analyzing an oscillator model describing the electron motions in the fiber medium, we can obtain the third-order susceptibility in the presence of the magnetic field. According to the Maxwell's equations and the minimal coupling principle in the metric expression of the curved space, we derive the propagation equations of light in a helically wound optical fiber. Finally, we have obtained the analytic expressions of Faraday rotation angle for both linearly and elliptically polarized lights, which explicitly indicates an important nonlinear correction on the Faraday rotation angles. Possible experimental observations and some implications of our theoretical findings are discussed.