Magnetic field sensors utilising diluted magnetic semiconductors

We present two different AC magnetic field sensing configurations exploiting the Faraday effect in the semiconductor compound Cd0.57Mn0.49Te. The first configuration is a typical polarimetric set-up; the periodic magneto-optic polarisation rotation of a linearly polarised input in the transducer crystal is converted into intensity modulation by means of a polarisation analyser. In the second configuration, the Faraday modulation appears in the electronic spectrum of the interference signal at the output of a hybrid Mach-Zender interferometer. Both set-ups include noise rejection schemes (although different in principle and operation) to improve the signal to noise ratio.