Ildar Salakhutdinov

Polymer-based surface-plasmon-polariton stripe waveguides at telecommunication wavelengths

Long-range surface-plasmon-polariton (LR–SPP) waveguiding along thin gold stripes embedded in polymer is investigated in the wavelength range of 1510–1620 nm. LR–SPP intensity distributions at the output are measured for different stripe widths and thicknesses. Coupling loss of ∼0.5 dB is achieved when exciting the fundamental LR–SPP mode along 10-nm-thick stripes of 6–10 μm width with a polarization maintaining fiber. LR–SPP propagation loss of 6–8 dB/cm is estimated (at 1550 nm) and attributed to scattering from inhomogeneities of the metal stripe and polymer cladding.

Nonlocal effects in effective-medium response of nanolayered metamaterials

We demonstrate that the majority pf plasmonic nanolayered composites, despite being subwanelength, are not described by effective medium theory and develop an adequate description of electromagnetism in these systems.

Highly confined optical modes in nanoscale metal-dielectric multilayers

We show that a stack of metal-dielectric nanolayers, in addition to the long- and short-range plasmon polaritons, guides also an entire family of modes strongly confined within the multilayer—the bulk plasmon polariton modes. We propose a classification scheme that reflects specific properties of these modes. We report experimental verification of the bulk modes by measuring modal indices in a structure made of three pairs of silica 29 nm/gold 25 nm layers. DOI: 10.1103/PhysRevB.75.241402 PACS numbers: 73.20.Mf, 42.25.Bs, 42.82.Et, 73.21.Ac Nanoscale confinement of light is of great interest for applications in sensing, imaging, all-optical signal processing, and computing. Subwavelength confinement attributed to gap plasmon polaritons GPPs has been demonstrated in a thin dielectric layer surrounded by metallic claddings. 1 Here we present another solution to subdiffraction confinement of light and show that a stack of metal-dielectric nanolayers guides a family of modes strongly confined within the multilayer—the bulk plasmon polariton BPP modes. The bulk modes have very short penetration depth into the claddings even if the claddings are made of dielectric materials. Their modal indices ratio of the light velocity in vacuum to the phase velocity of a guided mode are typically large in absolute value and may be both positive and negative. 2 We propose a classification scheme that reflects specific properties of BPPs. We verify BPPs experimentally by measuring their modal indices in a structure made of three pairs of silica-gold nanolayers. When considering light confinement in a waveguide, the

A simple miniature optical spectrometer with a planar waveguide grating coupler in combination with a plano-convex lens

A miniature optical spectrometer with a thin-film planar waveguide grating coupler in combination with a miniature plano-convex focusing lens has been investigated. With optical part of the spectrometer as small as 0.2 cubic cm, the spectral resolution varies from 0.3 nm to 4.6 nm within the wavelength range 488.0 nm - 632.8 nm.

Concept of a miniature optical spectrometer using integrated optical and micro-optical components.

We describe the concept of a super compact diffractive imaging spectrometer, with optical components a few millimeters across in all dimensions, capable of detecting optical fluorescence spectra within the entire visible spectral range from 400 nm to 700 nm with resolution of the order of 2 nm. In addition, the proposed spectrometer is capable of working simultaneously with multiple, up to 35, independent input optical channels. A specially designed diffractive optical element integrated with a planar optical waveguide is the key component of the proposed device. In the preliminary experimental tests, a uniform waveguide grating with a microlens was used to mimic operation of the diffractive optical element. A microspectrometer with optical components measured below 1 cm in all dimensions covers the spectral range from 450 nm to 650 nm and shows a spectral resolution of 0.5 nm at wavelengths close to 514 nm and 633 nm.

Nanopatterning effects on astrocyte reactivity.

An array of design strategies have been targeted toward minimizing failure of implanted microelectrodes by minimizing the chronic glial scar around the microelectrode under chronic conditions. Current approaches toward inhibiting the initiation of glial scarring range from altering the geometry, roughness, size, shape, and materials of the device. Studies have shown materials which mimic the nanotopography of the natural environment in vivo will consequently result in an improved biocompatible response. Nanofabrication of electrode arrays is being pursued in the field of neuronal electrophysiology to increase sampling capabilities. Literature shows a gap in research of nanotopography influence in the reduction of astrogliosis. The aim of this study was to determine optimal feature sizes for neural electrode fabrication, which was defined as eliciting a nonreactive astrocytic response. Nanopatterned surfaces were fabricated with nanoimprint lithography on poly(methyl methacrylate) surfaces. The rate of protein adsorption, quantity of protein adsorption, cell alignment, morphology, adhesion, proliferation, viability, and gene expression was compared between nanopatterned surfaces of different dimensions and non-nanopatterned control surfaces. Results of this study revealed that 3600 nanopatterned surfaces elicited less of a response when compared with the other patterned and non-nanopatterned surfaces. The surface instigated cell alignment along the nanopattern, less protein adsorption, less cell adhesion, proliferation and viability, inhibition of glial fibrillary acidic protein, and mitogen-activated protein kinase kinase 1 compared with all other substrates tested.

Sub-micron grating fabrication on hafnium oxide thin-film waveguides with focused ion-beam milling

Uniform period sub-micron gratings have been fabricated using focused ion beam milling on hafnium oxide waveguides. Atomic force microscopy indicates that the gratings have smooth and uniform profiles. At the period of 330 nm, the largest peak-to-peak height that was achieved was 85 nm. Scattering at the grating imperfections was found to be at least two orders of magnitude weaker than the intensity of the diffracted order.

Plasmonic nanolayer composites: coupled plasmon polaritons, effective-medium response, and subdiffraction light manipulation

Received 14 February 2007; Accepted 4 June 2007Recommended by Christian BrosseauWeanalyzetheevolutionofthemodesinnanoplasmonicmultilayeredstructuresandstudythetransitionoftheopticalpropertiesof these systems to the effective-medium regime. We derive the effective-medium parameters and study the validity of our analyt-ical results with exact numerical solutions of Maxwell equations. Finally, we explore the applications of multilayered systems forsubwavelength light confinement in planar and circular waveguides.Copyright

Fibronectin adsorption to nanopatterned silicon surfaces

The possibility of using surface topography for guidance of different biological molecules and cells is a relevant topic that can be applied to a wide research activity. This study investigated the adsorption of fibronectin to a diffraction grated silicon surface. The rectangular grating profile featured a controlled surface with 350 nm period and a corrugation depth of 90 nm. Results demonstrated that the controlled surface had a significantly positive effect on the fibronectin binding. Thus, nanoscale surface topography can enhance fibronectin binding.

Characterization of long-range surface plasmon-polariton in stripe waveguides using scanning near-field optical microscopy

Propagation characteristics of long-range surface plasmon-polariton (LRSPP) guiding along thin gold stripes embedded in polymer cover layers are investigated by scanning near-field optical microscopy (SNOM). It is shown that the characterization of samples with cover layers up to 10 μm is feasible in the optical communication wavelength range. We found that the spatial dimension of the optical signal is directly related to the geometrical dimension of the guiding layer, and the light collected by the SNOM is scattered light from the surface and not the evanescent field. We also discuss the limitations of the SNOM technique for the characterization of LRSPP modes.