D. O. Ignatyeva

Magneto-optical plasmonic heterostructure with ultranarrow resonance for sensing applications

Currently, sensors invade into our everyday life to bring higher life standards, excellent medical diagnostic and efficient security. Plasmonic biosensors demonstrate an outstanding performance ranking themselves among best candidates for different applications. However, their sensitivity is still limited that prevents further expansion. Here we present a novel concept of magnetoplasmonic sensor with ultranarrow resonances and high sensitivity. Our approach is based on the combination of a specially designed one-dimensional photonic crystal and a ferromagnetic layer to realize ultralong-range propagating magnetoplasmons and to detect alteration of the environment refractive index via observation of the modifications in the Transversal Magnetooptical Kerr Effect spectrum. The fabrication of such a structure is relatively easy in comparison with e.g. nanopatterned samples. The fabricated heterostructure shows extremely sharp (angular width of 0.06°) surface plasmon resonance and even sharper magnetoplasmonic resonance (angular width is 0.02°). It corresponds to the propagation length as large as 106 μm which is record for magnetoplasmons and promising for magneto-optical interferometry and plasmonic circuitry as well as magnetic field sensing. The magnitude of the Kerr effect of 11% is achieved which allows for detection limit of 1∙10−6. The prospects of further increase of the sensitivity of this approach are discussed.

Transformation of mode polarization in gyrotropic plasmonic waveguides

We analyze the gyration impact on the mode polarization in plasmonic waveguides containing dielectrics with natural optical activity, or gyration induced by magnetization in the polar configuration or the longitudinal configuration. It has been found that the gyration mostly affects the mode polarization that acquires additional optical field components proportional to the gyration coefficient, whereas the mode dispersion remains almost unchanged. Moreover, if the gyration coefficient is rather large, then the mode loses its localization. The polarization transformation can be two orders of magnitude stronger for structures with a thin metal film than that for the solitary interface. The polarization transformation of the plasmonic modes was demonstrated experimentally via measuring optical transmittance through a layered magnetoplasmonic structure. The resonance in the transmittance spectrum corresponding to the excitation of modes of the polarization orthogonal to that of incident light was observed. The polarization transformation is enhanced if the TM and TE modes are excited simultaneously. The described effect can be applied in sensors, plasmonic circuitry, and plasmonic-based light modulators.

Plasmonic pulse shaping and velocity control via photoexcitation of electrons in a gold film

We study the possibility of surface plasmon polariton (SPP) pulse shape, delay and duration manipulation on sub-picosecond timescales via a high intensity pump SPP pulse photoexciting electrons in a gold film. We present a theoretical model describing this process and show that the pump induces the phase modulation of the probe pulse leading to its compression by about 20% and the variation of the delay between two SPP pulses up to 15 fs for the incident fluence of the pump of 1.5 mJ∙cm⁻².

Surface plasmon polariton waves in optically active media

A theory of surface plasmon-polariton wave propagation along an interface of an optically active medium and metal or metamaterial has been developed. It is shown that optical activity leads to changing of cross section and polarization of the surface modes, whereas the propagation constant in first approximation does not depend on the gyrotropy coefficient.

High-Q surface modes in photonic crystal/iron garnet film heterostructures for sensor applications

A novel type of a plasmonic sensor based on a magnetophotonic plasmonic heterostructure with an ultrahigh-Q resonance is considered. A magnetoplasmonic resonance with an angular width of 0.06°, which corresponds to a Q factor of 700 and is a record value for magnetoplasmonic sensors, is experimentally demonstrated. It is shown that, owing to the excitation of long-propagation-range plasmons, the transverse magneto-optical Kerr effect is considerably enhanced and, thus, the sensitivity of the magnetoplasmonic sensor to variations in the refractive index increases to 18 RIU–1, where RIU is the refractive index unit. Numerical calculations indicate that the parameters of the magnetoplasmonic structure can be further optimized to attain sensitivities up to 5 × 103 RIU–1.

Enhancement of SPR-sensor sensitivity in garnet-based plasmonic heterostructures

We propose a novel approach to the enhancement of the SPR-sensors sensitivity via utilization of the specially designed garnet-based magnetoplasmonic heterostructures with one-dimensional photonic crystals. Excitation of the long-range propagating modes in such structures as well as the magnetooptical measurements instead of reflection ones make the investigated resonances extremely narrow thus significantly increasing the SPR sensor sensitivity.

Mathematical modeling of an open microcavity with a layer of metamaterial

We investigate the properties of an open Fabry-Perot microcavity containing a layer of metamaterial with a negative refractive index. Numerical simulation of this cavity is performed using an original program package based on the FDTD scheme, with allowance for the frequency dispersion of the media and the UPML absorbing boundary conditions. We demonstrate that waveguide eigenmodes with arbitrary profiles exist in such a cavity and the metamaterial lowers diffraction losses considerably.

Garnet-based magnetoplasmonic heterostructures with 1D photonic crystals for highly effective chemo- and biosensing

We present a novel type of magnetoplasmonic heterostructures containing one-dimensional photonic crystals.

Polarization properties of surface plasmon polaritons at the boundary of topological insulators with the axion effect

Properties of surface plasmon polariton waves are theoretically studied in structures containing topological insulators with the axion effect. The effect of axion properties on dispersion, localization, and polarization of plasmon polaritons is analyzed. A possibility of determining the axion effect from the variation in the plasmon-polariton polarization is shown, and conditions for enhancement of polarization effects are revealed in waveguide structures of the dielectric−metal−dielectric type.

Interaction of optical pulses in nonlinear plasmonic systems

We investigate the collision of the two surface plasmon polariton pulses interacting at the interface between noble metal and dielectric with Kerr nonlinearity. The dynamics of the signal and pump SPP pulse was analyzed using both spectral and trajectory approaches. We derived the conditions under which the reflection of the weak signal SPP pulse from the intense pump SPP can be observed. Using such interaction one can control the propagation dynamics of the signal pulse via the modulation of the intensity of the pump pulse.