Two orthogonal light polarizations in a waveguide overcoupled to microring resonators can propagate as fast and slow light. Which polarization is fast (slow) is determined by input polarization and the number of resonators.
We perform rigorous simulations of hybrid long-range modes guided by a central metal core and a two-dimensional dielectric slab. We show that these modes are subject to fewer limitations than conventional long-range plasmon modes in terms of field confinement and guiding performance. These hybrid modes may offer substantial improvements for integrated plasmonic components, as illustrated here by the consideration of 90° bends.
The propagation characteristics of a subwavelength plasmonic crystal are studied based on its complex Bloch band structure. Photonic crystal bands are generated with an alternative 2D Finite Element Method formulation in which the Bloch wave problem is reduced to a quadratic eigenvalue system for the Bloch wavevector amplitude k. This method constitutes an efficient and convenient alternative to nonlinear search methods normally employed in the calculation of photonic bands when dispersive materials are involved. The method yields complex wavevector Bloch modes that determine the wave-scattering characteristics of finite crystals. This is evidenced in a comparison between the band structure of the square-lattice plasmonic crystal and scattering transfer-functions from a corresponding finite crystal slab. We report on a wave interference effect that leads to transmission resonances similar to Fano resonances, as well as on the isotropy of the crystal's negative index band. Our results indicate that effective propagation constants obtained from scattering simulations may not always be directly related to individual crystal Bloch bands.
A ring resonator coupled to a waveguide can be used as a highly efficient polarization converter when the input is properly polarized. We model this phenomenon and verify the predictions with a demonstration of very efficient polarization conversion (>90%) on a silica microsphere coupled to a tapered optical fiber.
We present a design of a polarization converter between linear, circular, and elliptic accomplished with an on-chip high-Q dielectric microring resonator. Nonlinear polarization switching can be accomplished at modest input intensities because of the high-intensity compression in the ring. We predict an optical bistability effect making the polarization of the transmitted light dependent on its spectral or intensity history.
We experimentally demonstrate controlled polarization-selectivephenomena in a whispering gallery mode resonator. We observedefficient (≈75%) polarization conversion of light in a silica microspherecoupled to a tapered optical fiber with proper optimization of the polarization of the propagating light. A simple model treating the microsphere as a ring resonator provides a good fit to the observed behavior.
The phenomena of slow and super-luminal propagation of electromagnetic waves are considered in the context of a magnetized plasma with undulator induced transparency (UIT). Without the magnetic undulator, the plasma is opaque to the right-hand circularly polarized radiation at the electron cyclotron frequency. Addition of a helical undulator results in the dramatic slowing down of wave propagation. Super-luminal propagation occurs due to the strong coupling between the right- and left-hand circularly polarized waves. We demonstrate that, depending on the detected wave polarization, super-luminal and slow radiation can be observed at the same frequency. Moreover, the super-luminal signal can be controlled by the intensity of the incident signal.
An optical metamaterial characterized simultaneously by negative permittivity and permeability, viz. doubly negative metamaterial (DNM), that comprises deeply subwavelength unit cells is introduced. The DNM can operate in the near infrared and visible spectra and can be manufactured using standard nanofabrication methods with compatible materials. The DNM's unit cell comprise a continuous optically thin metal film sandwiched between two identical optically thin metal strips separated by a small distance form the film. The incorporation of the middle thin metal film avoids limitations of metamaterials comprised of arrays of paired wires/strips/patches to operate for large wavelength / unit cell ratios. Acavity model, which is a modification of the conventional patch antennacavity model, is developed to elucidate the structure's electromagneticproperties. A novel procedure for extracting the effective permittivity andpermeability is developed for an arbitrary incident angle and thoseparameters were shown to be nearly angle-independent. Extensions of thepresented two dimensional structure to three dimensions by using squarepatches are straightforward and will enable more isotropic DNMs.
The wave nature of light limits the spatial resolution in classical microscopy to about half of the illumination wavelength. Recently, a new approach capable of achieving subwavelength spatial resolution, called superlensing, was invented, challenging the already established method of scanning near-field optical microscopy (SNOM). We combine the advantages of both techniques and demonstrate a novel imaging system where the objects no longer need to be in close proxim-ity to a near-field probe, allowing for optical near-field microscopy of subsurface objects at sub-wavelength-scale lateral resolution.
The effect of spatial dispersion on the electromagnetic properties of a metamaterial consisting of a three-dimensional mesh of crossing metallic wires is reported. The effective dielectric permittivity tensor ϵij($ømega$,k) of the wire mesh is calculated in the limit of small wavenumbers. The procedure for extracting the spatial dispersion from the $ømega$ versus k dependence for electromagnetic waves propagating in the bulk of the metamaterial is developed. These propagating modes are identified as similar to the longitudinal (plasmon) and transverse (photon) waves in a plasma. Spatial dispersion is found to have the most dramatic effect on the surface waves that exist at the wire mesh-vacuum interface.