Novel interferometric magnetic field sensor based on the Faraday effect in diluted magnetic semiconductor crystals

We discuss the merits of low coherence interferometry to investigate the Faraday effect in a diluted magnetic semiconductor (DMS) crystal placed in one of the interferometer arm. We describe the combination of modulation effects due to the Farady effect in the DMS probe with the modulation due to a vibrating mirror in the interferometer. Essential for the measurement of the Verdet constant is the control of polarization in the two arms of the interferometer. We show that by watching the resulting spectra of the photodetected signal, clear distinction is possible between the circular and linear polarization of the input light.