This paper describes the TE-TM mode conversion in a magneto-optical layer made by a SiO2/ZrO2 layer doped with magnetic CoFe2O4 nanoparticles. The mode conversion is caused by the Faraday rotation if the magnetization is aligned along the z-axis, parallel to mode propagation. The properties of this phenomenon are simulated using the full-vectorial beam propagation method (BPM). The simulation results show clearly the inuence of two parameters in such devices, the rst one is the o-diagonal component of tensor that enhances the rotation and the second one, the imaginary diagonal tensor (parameters K ) which makes it suering from absorption. This result of simulation is an important step to achieve a monolithic integration of optical isolators.