Recently, research has been concentrated on the study of the magnetic nanoparticules for their use in the design of magneto-optical devices. The magneto-optical waveguides for example exploit the Faraday effect to obtain a rotation of polarization TE and TM independent of the propagation direction. In this work, we study isolating component whose operating principle is based on the minimization of the phase mismatch between TE and TM fundamental propagation modes. It appeared promising to use as a guiding film the thin layers doped by magnetic nanoparticules γ-Fe2O3 in order to carry out an adequate phase mismatch. This last can be adjusted by permanent linear birefringence resulting from the application of an external magnetic field during the gelation of the solution which constitutes the guiding film. Many studies were undertaken primarily to minimize the birefringence between TE and TM modes, for that this work represents a new potential means to reach the phase matching by acting on the anisotropy and the thin layer thickness. This condition can be realized in the waveguides with SiO2/TiO2 guiding thin layer doped by nanoparticules of maghemite γ-Fe2O3. The simulations carried out by the FMM method and MATLAB allowed to deduce the conditions to decrease the phase mismatch and increase the conversion ratio of TE/TM modes in order to ameliorate the isolation.