Low Temperature Physics: 42, 685 (2016); https://doi.org/10.1063/1.4961486
Plasmon-polaritons on surface with fluctuating impedance: Scattering, localization, stability
Yu.V. Tarasov, O.V. Usatenko, and D.А. Iakushev
Institute of Radiophysics and Electronics National Academy of Sciences of Ukraine, 12 Ac. Proskura Str., Kharkov 61085, Ukraine
Received March 1, 2016
Scattering of surface TM polarized plasmon-polariton waves (PPW) by a finite domain of metal–vacuum interface with randomly fluctuating surface impedance is examined. Solution of the integral equation relating the scattered field with a field of the incident PPW, which is valid for arbitrary scattering intensity and arbitrary dissipative characteristics of the conductive medium, is analyzed. As a measure of PPW scattering, the Hilbert norm of the integral scattering operator is used. The strength of the scattering is shown to be controlled not only by the parameters of the fluctuating impedance (dispersion, correlation radius, the length of inhomogeneity region) but also crucially depends on the conductivity of the metal. If the scattering operator norm is small, the PPW is mainly scattered into the vacuum, thus losing its energy for excitation of quasi-isotropic bulk Norton waves over the conducting surface. The scattered field intensity is expressed in terms of the random impedance pair correlation function, whose dependence on the incoming and scattered wavenumbers demonstrates the possibility to observe, under the random-impedance-induced scattering of PPW, the effect analogous to Wood anomalies of waves scattered by periodic gratings. Under strong scattering, when the integral operator norm becomes large as compared to unity, the radiation into the free space is highly suppressed, and, in the limit, the incoming PPW is almost ideally backward-reflected from the inhomogeneous part of the interface. Therefore, within the model of dissipation-free conducting medium the surface polariton is unstable against arbitrary small fluctuations of the medium polarizability. The mirroring of the scattering under strong fluctuations of the impedance is interpreted in terms of the Anderson localization.
PACS: 73.20.Mf Surface plasmons;
Key words: surface plasmon–polariton; surface impedance; metal–vacuum interface.
Published online: June 24, 2016