Anderson Localization of Surface-Plasmon Polaritons in Arrays of Metallic Nanowires

摘要

Anderson localization is a fundamental wave phenomenon occurring in various branches of physics. It was first predicted in solid state physics, where P. W. Anderson had found that the interference from multiple scatterings of the electron by random defects changes the original infinitely extended Bloch eigenmodes into exponentially localized modes. The Anderson localization was later extended to photons, and the true Anderson localization of light has been observed in randomly distorted one- and two-dimensional optical lattices. We study the effect of the structural disorder on the optical field localization in arrays of metallic nanowires. The disorder is expected to be important, as it is inherent to subwavelength structures and as such affect the functionality of the subwavelength plasmonic devices. In our work the disorder is introduced by randomly changing the radius of each nanowire around an average value while keeping the nanowires periodic on average. We demonstrate, from the first principles (solving the full set of 3D Maxwell's equations) that the field localization at the subwavelength scale in these structures is possible. Figure 1 presents such a localized Anderson mode (AM) in the one-dimensional metallic array. The dependence of the effective width of the AM on the disorder strength is also shown. Deep sub-wavelength localization is clearly demonstrated by the figure.