Polarization-tunable plasmon-enhanced extraordinary transmission through metallic films using asymmetric cruciform apertures

Plasmon-enhanced transmission of light incident on a periodic array of nanoscale, asymmetric cruciform patterns is demonstrated. The corresponding transmission spectra are shown to be polarization dependent and possess unique properties, such as the existence of isosbestic points for which the transmission is polarization insensitive. Transmission peaks corresponding to localized surface plasmon resonances and extended surface plasmons are also identified.     

Enhanced optical absorption for photovoltaics via excitation of waveguide and plasmon-polariton modes

We study theoretically the mechanisms by which optical absorption is enhanced in an optical nanostructure consisting of a slab waveguide, made of a-Si:H, sandwiched between a periodic array of metallic nanowires and a substrate, both made of Au. We demonstrate that for the TM polarization the optical absorption in the slab waveguide can be enhanced by almost an order of magnitude by the excitation of plasmon modes, whereas for both the TM and TE polarizations the grating-induced excitation of slab waveguide modes leads to more than twofold enhancement of the optical absorption.     

Anomalous diffusion in two-dimensional potentials with hexagonal symmetry

The diffusion process in a Hamiltonian dynamical system describing the motion of a particle in a two-dimensional (2D) potential with hexagonal symmetry is studied. It is shown that, depending on the energy of the particle, various transport processes can exist: normal (Brownian) diffusion, anomalous diffusion, and ballistic transport. The relationship between these transport processes and the underlying structure of the phase space of the Hamiltonian dynamical system is investigated. The anomalous transport is studied in detail in two particular cases: in the first case, inside the chaotic sea there exist self-similar structures with fractal properties while in the second case the transport takes place in the presence of multilayered structures. It is demonstrated that structures of the second type can lead to a physical situation in which the transport becomes ballistic. Also, it is shown that for all cases in which the diffusive transport is anomalous the trajectories of the diffusing particles contain long segments of regular motion, the length of these segments being described by Levy probability density functions. Finally, the numerical values of the parameters which describe the diffusion processes are compared with those predicted by existing theoretical models. (c) 2000 American Institute of Physics.