Alexander V. Korovin

Hybrid Colloidal Plasmonic‐Photonic Crystals

We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals.

Opals with a thin-film metallic defect-hybrid colloidal plasmonic photonic crystals

Hybrid photonic crystals consisting of a thin-film opal and a thin profiled gold film situated on the surface or inside the opal have been prepared. The optical transmittance spectra of hybrid crystals have been studied. It has been found that the spectra exhibit minima due to diffraction resonances in the photonic crystal and bands of enhanced transmission due to transfer of radiation through the metal film surface by plasmon polaritons. It has been shown that the transmittance spectra of hybrid crystals with a metal film on the surface are subjected to a stronger modification than the hybrids having a metal film inside the crystal.

Birefringent elements based on femtosecond laser-induced nanogratings

We report on the fabrication of birefringent optical components based on so-called nanogratings. These selforganized nanostructures with sub-wavelength periodicity are formed during femtosecond laser processing of transparent materials, resulting in characteristic birefringent modifications. Nanogratings provide the means for the direct inscription of customized birefringent elements with position-dependent retardation. We present our investigations on the formation process of nanogratings in fused silica and the influence of fabrication parameters, thereby identifying ways to systematically control the structural properties of the gratings. Consequently, we were able to fabricate nanograting-based birefringent elements with specific retardations in bulk fused silica.

Enhanced Dielectric Environment Sensitivity of Surface Plasmon-Polariton in the Surface-Barrier Heterostructures Based on Corrugated Thin Metal Films with Quasi-Anticorrelated Interfaces

A new approach to the formation of a 1D planar periodicity on the front of a plasmonic photodetector based on Schottky barrier is proposed. It allows forming a 1D planar periodicity with corrugation at the “metal/environment” interface by laser interference lithography using embedded chalcogenide wires, whereas the “metal/semiconductor” interface is flat that leads to reducing of surface recombination losses at Shottky barrier in contrary to the conventional technology for forming corrugated metal films on the semiconductor surface requiring chemical etching of the semiconductor substrate. In this case, the metal film interfaces are quasi-anticorrelated as opposed to correlated ones in the conventional technology. It has been theoretically predicted that the polarization sensitivity (Tp/Ts) strongly depends on the cross-sectional shape of chalcogenide wires and reaches a value of 8. Furthermore, it was theoretically found that the maximum sensitivity of the signal intensity on the environment refractive index is three times larger than for an equivalent structure obtained by conventional technology. Comparison of experimental data for the photocurrent in the case of two types of correlation between metal film interfaces demonstrates good agreement with numerical simulations.

Hybridization of Surface Plasmon Polariton and Photonic Crystal Modes in Bragg Mirror with Periodically Profiled Metal Film.

The hybridization of the plasmonic and guided modes in the case of one-dimension photonic crystal based on Bragg mirror terminated by a corrugated metal film has been demonstrated theoretically. The simulations have showed that the hybrid plasmonic-photonic mode is characterized by low broadening due to redistribution of the electric field intensity between photonic mode and surface plasmon polariton. It was found that the Q-factor and the polarisation sensitivity of these modes are about 144 and 25, respectively, that is 3 times greater than for surface plasmon polariton exciting in similar structure without Bragg mirror.

Interplay of Mie and Bragg resonances in partly ordered monolayers of colloidal spheres

The transformation of 2-dimensional slab photonic crystal into 2-dimensional photonic glass was achieved by gradually increasing the sphere spacing and by randomising the lattice. The materials were prepared by assembling colloidal particles at the air/water interface using a Langmuir-Blodgett trough and the subsequent deposition on glass substrates. Highly ordered monolayers were obtained by using colloids of one size, while use particles of two different sizes and different partial concentrations allows to increase the spacing of the larger spheres and to randomize the lattice. Changes in the spheres arrangements result in a change of in-plane light propagation from band-like to hopping photon transport.

Hybrid architectures: enabling 4-dimensional plasmonic-photonic crystals

In order to realize the regime of strong coupling between Bloch modes of periodically structured dielectric and surface plasmon polariton modes of corrugated metal film we prepared 2-dimensional slab hybrid plasmonicphotonic crystals. Angle-resolved transmission/reflectance spectroscopy was used to assess the composition of guided modes in such hybrid crystals. In the case of a monolayer photonic crystal encapsulated in a plasmonic waveguide we achieved the splitting of major resonances, which was interpreted in terms of mode hybridization and controlling the spatial localization of modes.

Unconventional optical Tamm defect states in metal-terminated opal photonic crystals

Optical Tamm surface states are formed in 3-dimensional photonic crystals coated by thin metal films. These states appear in registry with diffraction resonances and localize the electromagnetic energy in resonators formed by diffraction mirrors of lattice planes and metal semishells. Tamm defect states provide the bypass for light in the spectral range of photonic stop-bands and thus reduce the efficiency of the Bragg diffraction resonances. In spite of hidden nature of this effect, its magnitude is comparable to the extraordinary transmission associated with tunneling of surface plasmon polaritons, which are simultaneously excited at surfaces of corrugated metal film coating.

Hybrid metal-dielectric photonic crystals with enhanced plasmonic-photonic interaction

Control on the optical response of 2-dimensional colloidal photonic crystals was achieved by combining them with thin metal films. In such hybrids the light transport depends on the parameters of the sphere lattice and the topology of the metal film. This approach allows mixing Bloch modes and surface plasmon polariton modes in the total optical response of hybrid architectures. Stronger modification of the hybrids optical properties was achieved in the case of tighter light confinement.

Heterogeneous hybrid plasmonic-photonic crystals for enhanced light- matter interaction

Enhanced light- matter interaction in 3D photonic crystals (PhCs) is usually obtained by embedding defects for light confinement. However, in the case of opal-based PhCs, the reported quality factor of planar defects was not better than that of Fabry-Perot oscillations. In this presentation we demonstrate that stronger light confinement and/or its longer dwell times can be achieved using hybrid metal-dielectric PhCs.