The magneto-plasmonic response in planar multilayer with prism coupling composed from Fe and Au bilayer supplied by photonic crystal (Ta<sub>2</sub>O<sub>5</sub> / SiO<sub>2</sub>) is studied. Modeled structure is intended as a sensor unit combining magneto-optical (MO) and surface-plasmon-resonance (SPR) effects. The sensitivity of MO-SPR system by small variations of analyte refractive index is tested to obtain optimal resolution ability.
A measurable magneto-optical activity of nanoparticles made out of noble metals is observed when the localized plasmon waves are excited in the presence of external magnetic field. We confirmed these observations for quite general Au nanostructure on SiO2/Si substrate theoretically and by experimental way. The heterogeneous layer is formed as a field of cylindrical or spheroidal nanodots of various size having the same height and parallel symmetry axis. These properties enable to apply the Bruggeman’s model of effective medium approximation, for which the size of dots (height, diameter) and fill-factor of nanodots were specified using the transmission electron microscopy image processing. Actually, this model is extended about the interaction of magnetic dipole moments simulated using discrete dipole approximation via geometrical averaging. Derived computational algorithm leads to better agreement with experimental data in the form of Kerr angles in polar configuration at visible spectral region. Obtained out-puts also illustrate the fact that extinction peak of plasmon excitation is located at the resonance wavelength of permittivity.
The non-reciprocity of magneto-optical reflection response by surface plasmon excitation in the planar Au/Fe/Au/glass nano-systems with prism coupling is studied. These structures are intended as magnetic field sensor units combining magneto-optical (MO) and surface-plasmon-resonance (SPR) effects. The ability of MO-SPR systems to magnetic field sensing is analysed using incidence-angle-depending response function (R<sub>pp</sub> <sup>(+)</sup> – R<sub>pp</sub> <sup>(-)</sup>)/(R<sub>pp</sub><sup> (+) </sup>+ R<sub>pp</sub><sup> (-)</sup>), where R<sub>pp</sub> denotes the reflectance of <i>p</i>-polarized beam; and, the sign in upper index relates to the orientation of external magnetic field. The proposed sensitivity criteria <i>F</i> and <i>K</i> (the magnitude and inflexed tangent of the response function oscillation) are applied in transverse MO configuration. Mathematical model based on the own matrix algorithm is applied to simulate the diffraction response to varying external magnetic field at the wavelength 632.8 nm. Obtained theoretical results are compared with experiments realized using the measuring device Multiskop (Optrel GbR, Germany).
The paper is devoted to Au/Fe/Au/glass and Au/Fe/glass structures intended as MO SPR sensor units. The model approach based on matrix algebra is used to describe the response of discussed structures to external magnetic field. The theoretical results are confirmed by experiments realized by Multiscope device. The attention has been focused on a sensitivity of proposed response factors ρ<sup>±</sup>(Φ) and <i>F</i> to magneto-optical effects. The application of ρ<sup>±</sup>(Φ) response factor for our structures description is limited. The <i>F</i> factor has practically linear character such as change of external magnetic field and ferromagnetic thin film thickness.
In the presented paper we summarize some results obtained by testing the recently prepared mathematical model for an inverse optical scattering problem. The computational scheme is based on the matrix model of the multilayer  and implemented in Matlab-code which uses the built-in Nelder-Mead algorithm for non-linear regression.