Dielectric coated conductive rod resonantly coupled with a cut transmission line as a tunable microwave bandstop filter and sensor.

The resonant interaction of a dielectric-coated conductive rod with the X-band microwave field is investigated. The magnetic field distribution of the Goubau standing radial surface waves was experimentally visualized by using a thermo-elastic optical indicator microscope, and the corresponding electric field distribution was determined via numerical simulations. These field distributions are characterized by a certain pattern of antinodes distinctive for standing waves.

Tunable ultra-broadband terahertz metamaterial absorber based on vanadium dioxide strips.

A simple design of an ultra-broadband metamaterial absorber (MMA) of terahertz (THz) radiation based on vanadium dioxide (VO) configurations is proposed. The system is composed of a top pattern representing orderly distributed VO strips, a dielectric spacer and an Au reflector. Theoretical analysis based on the electric dipole approximation is performed to characterize the absorption and scattering properties of an individual VO strip.

Maximizing absorption and scattering by spherical nanoparticles.

The absorption and scattering resonances of metal nanostructures are often assumed to be defined by the same condition of localized surface plasmon resonance. Using an electrostatic approximation, we demonstrate that the absorption and scattering cross sections of spherical nanoparticles reach their maxima at different wavelengths, which in turn differ from that defined by the Fröhlich condition (FC). These deviations from the FC originate from and are proportional to the material absorption.

Core-shell particles as efficient broadband absorbers in infrared optical range.

We demonstrate that efficient broadband absorption of infrared radiation can be obtained with deeply subwavelength spherical dielectric particles covered by a thin metal layer. Considerations based on Mie theory and the quasi-static approximation reveala wide range of configuration parameters, within which the absorption cross section reaches the geometrical one and exceeds more than by order of magnitude the scattering cross section in the infrared spectrum. We show that the absorption is not only efficient but also broadband with the spectral width being close to the resonant wavelength corresponding to the maximum of the absorption cross section.

Characteristics of light transfer in the connected conical waveguides with the same symmetry axis.

The propagation of the light trough dielectric-metal-dielectric conical waveguide is described by the coupling modes between internal and external waveguides. The energy pumping from internal to the external waveguide has a resonant behavior and is very sensitive to the variations of the system parameters. The simplified model of this process realization is the light flash at the end of the conical metal covered tip of the optical fiber that crosses the liquid-air interface.

Enhanced nonresonant light transmission through subwavelength slits in metal.

We analytically describe light transmission through a single subwavelength slit in a thin perfect electric conductor screen for the incident polarization being perpendicular to the slit, and derive simple, yet accurate, expressions for the average electric field in the slit and the transmission efficiency. The analytic results are consistent with full-wave numerical calculations and demonstrate that slits of widths ∼100  nm in real metals may feature nonresonant (i.e.

Relaxation dynamics of a quantum emitter resonantly coupled to a coherent state of a localized surface plasmon.

We investigate the relaxation dynamics of a quantum dipole emitter (QDE), e.g., a molecule or quantum dot, located near a metal nanoparticle (MNP) exhibiting a dipolar localized surface plasmon (LSP) resonance at the frequency of the QDE radiative transition.

Scaling in light scattering by sharp conical metal tips.

Using the electrostatic approximation, we analyze electromagnetic fields scattered by sharp conical metal tips, which are illuminated with light polarized along the tip axis. We establish scaling relations for the scattered field amplitude and phase, and verify the validity with numerical simulations. Analytic expressions for the wavelength at which the scattered field near the tip changes its direction and for the field decay near the tip extremity are obtained, relating these characteristics to the cone angle and metal permittivity.

Relaxation dynamics of a quantum emitter resonantly coupled to a metal nanoparticle.

The presence of a metal nanoparticle (MNP) near a quantum dipole emitter, when a localized surface plasmon mode is excited via the resonant coupling with an excited quantum dipole, dramatically changes the relaxation dynamics: an exponential decay changes to step-like behavior. The main physical consequence of this relaxation process is that the emission, being largely determined by the MNP, comes out with a substantial delay. A large number of system parameters in our analytical description opens new possibilities for controlling quantum emitter dynamics.

Plasmonic black-hole: broadband omnidirectional absorber of gap surface plasmons.

Using the effective-index approximation we show that touching spherical metal surfaces form a broadband omnidirectional absorber of gap surface plasmons (GSP), concentrating all GSP waves travelling within a certain radius at the point of contact (at which the field intensity tends to infinity even in the presence of metal absorption) and representing thereby a two-dimensional analogue of an optical black-hole realized without use of metamaterials. The developed wave analysis is supplemented with the geometrical optics (adiabatic) description providing explicit expressions for the critical radius (radius of the event horizon) and buildup of field enhancement along ray trajectories.

Adiabatic nanofocusing of channel plasmon polaritons.

Using the analytical description of channel plasmon polaritons (CPPs) developed recently [Opt. Lett.34, 2039 (2009)], we consider the adiabatic CPP nanofocusing in V grooves with linearly decreasing groove angles, deriving closed-form expressions for local field enhancements.

Analytic description of channel plasmon polaritons.

Using the effective-index approximation along with the explicit expression for the propagation constant of gap surface plasmons established recently [Opt. Express16, 2676 (2008)], we derive closed-form expressions for channel plasmon polariton (CPP) modes supported by V grooves cut into metal. The CPP field distributions and mode characteristics are calculated for the air-gold configuration.

Channel plasmon polaritons guided by graded gaps: closed-form solutions.

Using the effective-index approximation along with the explicit expression for the propagation constant of gap surface plasmons established recently [Opt. Express 16, 2676-2684 (2008)], we develop an analytic description of channel plasmon polariton (CPP) modes guided along V-grooves and gaps between two metal cylindrical surfaces. The results obtained for V-grooves are compared with those reported previously.