Faraday Magneto Optic Effect

Determination of Verdet Constants using Faraday Magneto-Optic Effect

In this first year lab project I aimed to measure the Verdet constants – that is, a measure the degree by which polarized light is ‘twisted’ when passing through a material inside a magnetic field. This was undertaken as a Semester 1 lab project in Year 1.

Verdet constants relate the rotation of polarized light traveling through a material, in a magnetic field, to the magnetic field strength. In the following experiment, an attempt was be made to measure the Verdet constants for BK7 (Crown Glass), SF18 (Flint Glass), Perspex and YAG (Yttrium Aluminium Garnet). The constants obtained were in agreement several sources; with values of (0.0137±0.0021), (0.0379±0.0021), and (0.0102±0.0026) for BK7, SF18 and Perspex respectively. Results for the Verdet constant of YAG were not found as it could not be determined whether the Faraday effect observed for YAG was due to the air or YAG as the calculated Verdet constant (although statistically insignificant when maximum errors were taken into account) was of the same order of magnitude of air. Thus, the effect could have been due to a combination of YAG (which had a very weak internal field, hence a small Verdet constant) and the air or the YAG had no effect and the only the Verdet constant for the air was measured.

Abstract from Report
Written by Edward Webster

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