Magnetically-tunable cutoff in asymmetric thin metal film plasmonic waveguide

摘要

We theoretically investigated the magnetically tunable cutoff of long-range surface plasmon polari-ton along thin metal film surrounded by a magneto-optic material on one side and by a nonmagnetic dielectric on the other. The analytically derived cutoff condition predicts that a magnetic field bias can induce a novel degenerate cutoff-state near which the beyond-cutoff radiation on one side can be switched to that on the other by a minor variation of the magnetic field from the bias. The magnetization bias needed for the degeneracy is proportional to the metal film thickness and inversely proportional to the wavelength