Low-loss waveguides (WGs), which support excitation of waveguide modes (WMs), are based on a dielectric WG separated from an absorptive film by a low-index dielectric spacer layer. We perform numerical and analytical study of the impact of the losses imposed to the WG in a planar sensing structure in the Kretschmann configuration on the resonance properties of the excitation. We demonstrate that the loss degree of the WMs can be controlled by the thickness of the spacer layer for both s and p polarizations. Extremely narrow resonances are discovered in the reflectivity spectra due to excitation of the low-loss WMs, and the maximum of the estimated sensitivity by intensity is found to be of 10 ⁵ -fold higher as compared to the conventional surface plasmon and WG-coupled surface plasmon sensors. We reveal the giant field intensity enhancement of 10 ⁷ -fold on the surface of the sensing structure in aqueous sensing media that can provide stronger fluorescence intensity at lower sample volumes for fluorescent labeling sensing.

Attenuated total reflection spectra of planar metal-dielectric structures obtained in the Otto and Kretschmann configurations exhibit resonance dips due to excitation of surface-plasmon polaritons. Although the dips have asymmetric line shapes, the asymmetry has not received much attention and the Lorentzian symmetric line shape has commonly been used in the spectral analyses. We analyze the reflectivity spectra of two- and three-layer plasmonic systems based on the electromagnetic and coupled-mode theories, and demonstrate that the asymmetric line shapes can be regarded as the Fano line shapes. In the resonance region, the spectra calculated as Fano line shapes using our approximate expressions are in excellent agreement with those obtained by rigorous electromagnetic calculations. The present formulations of the reflectivity allow us to gain insight into physical origins of characteristic behavior of the plasmonic resonances.

In this work, technologies of analog optical computing for image edge detection using flat interfaces between dielectrics are studied both theoretically and experimentally. The feasibility of analog differentiation and edge detection by using the Brewster effect for polarized light sources is demonstrated. The efficiency of the analog image processing is investigated using a variety of amplitude and phase masks.

In this paper we synthesized and measured optical characteristics of an azopolymer based on the polymer N-epoxypropylcarbazole and chromophore 4 - (4-nytrophenylazo)-aniline. Regularities in surface microstructure formation under the influence of a Gaussian beam focused on the synthesized polymer film were shown. With the linearly polarized incident laser beam, the anisotropic formation of the surface microstructures was demonstrated. The dependence of the microstructure formation on the incident beam power density was studied. Also, we experimentally investigated the nonlinear optical effects emerging in the azopolymer structure exposed to a high-intensity laser beam. Nonlinear topographic effects arising during the formation of microstructures by means of linearly and elliptically polarized beams were described.

To reveal origins of resonance characteristics of multilayer interference structures, we developed an ab initio spatial coupled-mode theory using the approximations of general electromagnetic theory of wave propagation in stratified media. In contrast to the conventional coupled-mode theory, the coefficients of developed coupled-mode models, which describe the Fano resonance behavior of interference field enhancement, are given by analytical functions of structural and optical parameters of the resonance systems. The results of analytical modeling of low- and high-loss resonator systems supporting waveguide, Fabry-Pérot, symmetric, and antisymmetric plasmonic normal modes agree very well with electromagnetic numerical simulations. We demonstrate also that the conventional spatial phenomenological coupled-mode theory is accurate only for low-loss structures.