Complex and interesting electromagnetic behavior can be found in spaces with non-flat topology. When considering the properties of an electromagnetic medium under an arbitrary coordinate transformation an alternative interpretation presents itself. The transformed material property tensors may be interpreted as a different set of material properties in a flat, Cartesian space. We describe the calculation of these material properties for coordinate transformations that describe spaces with spherical or cylindrical holes in them. The resulting material properties can then implement invisibility cloaks in flat space. We also describe a method for performing geometric ray tracing in these materials which are both inhomogeneous and anisotropic in their electric permittivity and magnetic permeability.

We present a method of fabricating single crystal silver nanowires based on the electroless deposition of silver into the pores of the polycarbonate membranes by the metal amplification process. A gold film on one side of the nanoporous membrane is used as the initiation layer for the silver crystal growth, while the pores of the membrane are used for guiding the growth of the silver crystal into a cylindrical nanostructure. Optical microscopy and spectroscopy of individual nanowires, transmission electron microscopy (TEM), and TEM diffraction crystallography were used to characterize the silver nanostructures. The metal amplification technique presents an electroless, simple, and inexpensive solution to the challenge of fabricating silver nanowires for electronic, optical, and biological applications.

SummaryWe study numerically two-dimensional nanoparticles with a non-regular shape and demonstrate that these particles can support many more plasmon resonances than a particle with a regular shape (e.g. an ellipse). The electric field distributions associated with these different resonances are investigated in detail in the context of near-field microscopy. Depending on the particle shape, extremely strong and localized near-fields, with intensity larger than 10 5 that of the illumination wave, can be generated. We also discuss the spectral dependence of these near-fields and show that different spatial distributions are observed, depending which plasmon resonance is excited in the particle.

A lateral beam shift is demonstrated both theoretically and in microwave experiments when total internal reflection takes place at the boundary of a self-collimating two-dimensional photonic crystal consisting of an array of high index dielectric cylinders. We further show the dependence of this shift on the cut of the last row of cylinders that defines the crystal interface. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3085768͔It is well known that totally reflected beams at a dielectric-air surface suffer a lateral shift. This is the extensively studied Goos-Hänchen effect, 1 which is an inherent diffraction effect for an incident beam. The wave components that compose an incident Gaussian beam suffer a nonuniform phase shift upon reflection and contribute to a net offset of the beam. The energy flow between the incident and shifted reflected beams is mediated by evanescent waves on the transmission side ͑air͒ of the interface. A similar effect has been discussed in photonic crystals ͑PCs͒ when a Gaussian beam impinges from the air with a frequency in the bandgap. 2,3 In this paper we demonstrate another beam shifting phenomenon that arises in PCs when a guided beam, internal to the crystal, is reflected off a crystal/air interface. It has a certain analogy with the aforementioned Goos-Hänchen 1 shift, but as we shall see, it occurs at a unique angle of reflection. We remark that a closely related work has recently been reported. 4,5 Self-waveguiding crystals have been studied in several works both experimentally 6 and theoretically. 7-9 Here, we consider a PC configuration consisting of a two-dimensional square lattice of dielectric cylinders. Its waveguiding properties are based on the choice of a particular frequency at which the dispersion isofrequency line is squarelike. 8 This leads to a collimation effect in privileged directions that happen to be along ⌫M. This is due to the fact that modes inside the PC will propagate with a group velocity given by g = ٌ k ͑k͒, and consequently, the direction of propagation will be perpendicular to the flat portion of the isofrequency contour.We have built a 2D square PC lattice made of cylinders of flint glass ͑0080 Corning glass͒ with permittivity of ⑀ Ϸ 7 + 0.08i in the studied range of frequencies. The PC structure was formed by inserting the glass rods into a matrix of drilled holes in a block Styrofoam material. The refractive index n of Styrofoam is very approximately n = 1 at these frequencies. The crystal has a lattice constant a = 7.57 mm and the cylinder radius r is r = 0.35a = 2.65 mm. The crystal is illuminated at a frequency of = 11.76 GHz. The sample was introduced in a parallel-plate waveguide, which is comprised of two flat conducting ͑Al͒ plates spaced 11 mm apart. 10 Microwaves were introduced through an X-band ͑8 to 12 GHz͒ coax-to-waveguide adapter that was attached to the lower plate. A 1.5 cm wide guide was constructed out of 10 db/cm absorber along the path from the antenna to the sample to form the incident beam. The sample rested on...