The Study of the Faraday Effect and the Faraday Rotation Ammeter, a Senior Project Thesis

TL;DR

This thesis explores the design and measurement of a Faraday Rotation Ammeter using fiber optics and the Faraday Effect to measure magnetic fields and current density, with a focus on improving sensitivity and accuracy.

Contribution

It demonstrates the simulation, measurement, and potential enhancement of a fiber optic Faraday Rotation Ammeter for precise current density measurements.

Findings

Measured the Verdet Constant for the chosen material.

Rebuilt and tested the FRA device.

Identified components for sensitivity improvements.

Abstract

The Faraday Rotation Ammeter (FRA) experiment takes advantage of the Faraday Effect in order to measure the current density in a given environment. The Faraday Effect explains a rotation of a polarized electric field as it propagates through a magnetic field. The FRA uses a polarized laser source that is coupled into fiber optic cable, then placed in the desired environment to measure the change of polarization angle caused by the magnetic field. The change in the angle of polarization can be used to then find the strength of the magnetic field and ultimately the level of current that created it. The Faraday Effect is amplified by the Verdet Constant, a material property that describes the number of degrees the angle of polarization rotates for a given medium. The device is intended to measure the current density seen in the Aurora. Estimated current values are expected to be around the lower micro-amps range (10-100mA/m^2) for that application. The main goals of the project were to simulate the Faraday Effect on the propagation of the linear polarized light wave, measure the Verdet Constant, re-build the previous design and determine what components of the design if improved or replaced with newer technology could provide the FRA the required sensitivity.