Optimization of a magneto-optical light modulator - Part I: Modeling of birefringence and Faraday effect

A comprehensive algorithm for the optimization of the parameters of a magneto-optical light modulator is presented and can be used as a guideline for finding the proper material for a particular application. Starting from the known material parameters as complex refractive index n(o) and complex magnetooptical constant Q, the optimum angle of incidence and polarization status of the considered lightwave and the optimum analyzer angle have to be found in order to attain the maximum signal-to-noise ratio (SNR) at the detector output. In case of the Faraday-effect the optimum thickness of the magneto-optical medium has to be found additionally. Besides the inherent magnetooptical effects of the ferromagnetic medium a possibly existing natural birefringence of the material is taken into account. The theory is formulated in terms of the Fresnel coefficients and gives the solution for the three fundamental effects (longitudinal, polar, and transverse) for the most important magneto-optical materials.