Transformation of mode polarization in gyrotropic plasmonic waveguides

We analyze the gyration impact on the mode polarization in plasmonic waveguides containing dielectrics with natural optical activity, or gyration induced by magnetization in the polar configuration or the longitudinal configuration. It has been found that the gyration mostly affects the mode polarization that acquires additional optical field components proportional to the gyration coefficient, whereas the mode dispersion remains almost unchanged. Moreover, if the gyration coefficient is rather large, then the mode loses its localization. The polarization transformation can be two orders of magnitude stronger for structures with a thin metal film than that for the solitary interface. The polarization transformation of the plasmonic modes was demonstrated experimentally via measuring optical transmittance through a layered magnetoplasmonic structure. The resonance in the transmittance spectrum corresponding to the excitation of modes of the polarization orthogonal to that of incident light was observed. The polarization transformation is enhanced if the TM and TE modes are excited simultaneously. The described effect can be applied in sensors, plasmonic circuitry, and plasmonic-based light modulators.