Split ring resonator (SRR) has attracted wide attentions since the discovery of negative refraction in 2002. Here, we
designed and fabricated vertical SRR (VSRR) arrays and toroidal metamolecule by using double exposure e-beam
lithography with precise alignment technique, and their resonance behaviors are subsequently studied in optical region.
The fundamental resonance properties of VSRR are studied as well as the plasmon coupling in a VSRR dimer structure
by changing the gap distance between SRRs. In addition, we proposed a three-dimensional toroidal structure composed a
VSRR with a dumbbell structure that supported a toroidal resonance under normal incidence with broadband working
frequency. Such toroidal metamaterial confines effectively the electric as well as magnetic energy paving a way for
promising applications in the field of plasmonics, such as integrated 3D plasmonic metamaterials, plasmonic biosensor
and lasing spaser.
Metamaterials are composites consisting of artificial
meta-atoms/metamolecules with typical sizes less than the
wavelength of operation. One of the key properties that makes metamaterials distinctly different form the natural media is
a very strong magnetic response that can be engineered in the visible and infra-red part of the spectrum.
In this work we summarize our multipole expansion approach that can be used to describe analytically optical properties
of metamaterials composed of, in particular, the split-ring and
cut-wire resonators. An important feature of our
formalism is the possibility of describing nonlinear response of a metamaterial, such as second harmonic generation,
which arises due to induced high-order multipoles.
Our model has recently been extended to the case of hybrid metamaterials composed of plasmonic nano-resonators
coupled with quantum elements (such as quantum dots, carbon nano tubes etc). It has also been shown that apart from
metamaterials various other physical systems can be successfully modelled within framework of the developed approach.
For example, transient dynamics and steady-state regime of a
nano-laser, as well as its stochastic properties (e.g.
linewidth of generation) have been described using this model.
Some basic properties of nonradiating systems are considered. A simple connection is established between the existence of residual electromagnetic potentials and the current density spectrum of the system. The properties of specific configurations based on toroidal and supertoroidal currents are modeled with the finite-difference time-domain method. Possible applications are discussed. A design of a new type of nonradiating system, based on a left-handed metamaterial is proposed and the system performance is modeled numerically.
We have found recently that Gallium, confined at an interface with silica, responds dramatically to low power optical excitation when held at temperatures close to its melting point (29.8<sup>o</sup>C). Intensities of just a few kW/cm<sup>2</sup> can reversibly modulate the intensity (by up to 40%) and phase (by as much as several degrees) of reflected light as the result of a light-induced structural transition occurring in a layer of gallium of only a few nm thick. Here, we report that this concept - of achieving a nonlinearity via a light-induced transformation in a confined solid at a temperature close to a phase transition temperature - can also be applied to gallium nanoparticles. We present the transient all-optical switching characteristics of gallium nanoparticle films comprising particles, typically 80 nm in diameter, which were formed directly on the ends of optical fibers using a new light-assisted self-assembly technique. We also report, for the first time, that this light-induced structural transition in gallium confined at an interface with silica underlies a new mechanism for photoconductivity. In our opinion, the exploitation of the light-induced phase transition in gallium may be a means of enabling the development of nanoscale photonic devices.
It is shown that a high concentration of laser-induced point defects (interstitials, vacancies), interacting with each other through deformation field, phase transition with formation of nanometer periodic Defect-Deformational- structure occurs, accompanied by appearance of modulation of the surface relief. The shape, period and amplitude of relief modulation are determined as functions of defect concentration. It is shown that the local field factor at metal surface undergoes resonance increase (10<SUP>2</SUP> times) under scanning of the temperature in vicinity of roughening transition point lying just below the melting point.