A comparative study on the measurement of verdet constant of magneto-optic glass by different techniques

Accurate measurement of Verdet constant of magneto-optical glasses is integral to the realization of Faraday effect based photonic devices meant for many scientific and technological applications. Various techniques are employed for the measurement of Verdet constant using both the dc and ac magnetic field. In this paper, a comparative study of these techniques has been carried out. Pros and cons of these techniques have been analyzed theoretically and experimentally. The results show that the precision of the measurement by dc magnetic field is limited by the requirement of large magnetic field and accuracy of measurement of the rotation angle. The techniques using small ac field are more accurate and eliminate the requirement of external arrangement for rotation angle. The first and second harmonics can be used to measure the Verdet constant with comparable accuracy. The inhomogeneity of magnetic field in both techniques was found to have a considerable effect on the measurement accuracy.