Khachatur V. Nerkararyan

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. Calculations at telecom wavelengths predict the possibility of reaching the intensity enhancements exceeding approximately 1200 for realistic groove tapers cut into gold. Our conclusions are in good agreement with the results of previous investigations.

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. The results obtained are found to be in good agreement with the results of previous numerical simulations.

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. Dispersion of the main CPP characteristics is calculated for air-gold configurations, allowing one to design graded-gap waveguides for the single-mode operation supporting well-confined fundamental CPP modes in a broad wavelength range.

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.

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.

Ring-type V-groove surface plasmon microresonator: The modal structure and Q-factor

We consider the formation of the surface plasmon polariton (SPP) mode in the ring-type V-groove structure. Closed-form expressions for the mode field distributions, resonant frequency, and total quality factor are obtained for the structure in a broad wavelength range. The model serves as a practical guide to design a SPP microcavity with sub-wavelength confinement in the transverse cross sectional directions.

A Surface Plasmon Microcavity Between the Toroidal and Flat Metallic Surfaces

We consider the formation of the surface plasmon polariton (SPP) mode in the structure with a metallic torus and a metallic flat surface separated by a dielectric medium. The energy of the wave field is mainly concentrated in the dielectric medium at the vicinity of the minimum thickness of the gap between the metallic surfaces. The dependence of the resonant frequency on parameters of the structure was determined. The strongly localized SPP mode in the transverse direction contributes to the increase in the Purcell factor that is crucial for enhancement of the spontaneous emission rate.

Nature of the enhancement of the nonlinear optical response from rough surface of a metal

The geometric peculiarities of the rough surface of a metal are revealed, when due to the essential shortening of the wavelength of the surface polariton excited by the light localization in a very small region of a space take place.

Dynamics of a quantum emitter resonantly coupled to both external field and localized surface plasmon

We investigate excitation dynamics in the system of a quantum dipole emitter (QDE) coupled to a located nearby metal nanoparticle (MNP), which exhibits a dipolar localized surface plasmon (LSP) resonance at the frequency of the QDE radiative transition, in the presence of a strong external resonant electromagnetic field. Considering the QDE-field interactions in the regime of strong QDE-field coupling, we show that the feedback provided by the MNP on the QDE (due to the LSP excitation with the field generated by the dipole moment of the QDE transition) influences significantly the coherent process of Rabi oscillations, resulting in the occurrence of additional satellite frequencies in the radiation spectrum scattered by the QDE-MNP configuration. The relative ratio of high harmonics depends strongly on the QDE-MNP separation, an important characteristic feature that can be used for observing this effect and exploited, for example, for controlling distances at nanoscale.

FIR Cherenkov-type difference frequency generation in a nonlinear optical waveguide

The far-infrared Cherenkov-type difference frequency generation (CDFG) in a planar optical waveguide is analyzed theoretically. The general expression for the CDFG angular distribution is given. The novel doubly resonant cavity is proposed. The CDFG efficiency enhancement due to resonant both at the optical and FIR frequencies is estimated to be a factor a few thousands.