Magneto-Optical Sensing Utilizing the Faraday Effect in Bulk Cd₁₋ₓMnₓTe

Author

Jeff C. Adams, University of Rhode Island

Date of Award

1988

Degree Type

Thesis

Degree Name

Master of Science in Electrical Engineering (MSEE)

Department

Electrical Engineering

First Advisor

Harish R. D. Sunak

Abstract

A magnetic field sensor utilizing the Faraday effect in bulk Cd_1-xMn_xTe was investigated. The magnetic field sensitivity was found theoretically as a function of various system parameters and compared with experiment.

The magneto-optical Verdet constant of Cd_.5Mn_.5Te was measured at a wavelength of 633 nm, and found to be 0.15° cm^-1Gauss^-1. The optical absorption was measured to be 0.9cm^-1, and the refractive index 3.1; all values agreed well with published measurements.

A polarization preserving fiber was used to link the Cd_.5Mn_.5Te sensor in a polarization-rotated reflection scheme in order to cancel environmentally induced linear birefringence fluctuations which contribute to system noise. The linear birefringence fluctuations were modeled as a gaussian distributed random variable and included in the formulation of the sensing system's signal-to-noise ratio. Since the standard deviation of the birefringence fluctuations was not known a priori, its value was chosen to match theory with experiment, and then compared with data fro recently published papers examining the statistics of linear birefringence fluctuations in polarization-preserving fibers; published values of the standard deviation of birefringence fluctuations for a given environmental perturbation compared reasonably with values inferred from our experimental data. Experimental results showed a marked improvement in the magnetic sensor's signal-to-noise ratio using this method of polarization-rotated reflection.

Recommended Citation

Adams, Jeff C., "Magneto-Optical Sensing Utilizing the Faraday Effect in Bulk Cd₁₋ₓMnₓTe" (1988). Open Access Master's Theses. Paper 838.
https://digitalcommons.uri.edu/theses/838