Ilchenko S. Оptical resonance properties of metal-dielectric multilayer nanostructures.

The thesis is devoted to the experimental research of a new metal - dielectric multilayer nanostructure. It combines the properties of multilayer dielectric structures, such as Bragg mirrors, and metal nanolayers. Its main feature is the narrow spectral-angular resonance (<1 deg) at incident angles greater than the critical angle of total internal reflection. The sensitivity of the proposed structure as a refractive index sensor is compared with a known plasmon sensor according to the Kretschman scheme. It is shown that a dielectric structure with a metal layer can increase the sensitivity of the sensor by almost two orders of magnitude. The characteristics of the optimized structure, obtained in calculations, have been confirmed experimentally. Analysis of the dispersion curves reveals the region of narrow resonance for the reflection and field gain in a wide range of wavelengths (400-1600 nm) and incident angle (0-90 deg). Tamm modes in the resonant structure have been experimentally investigated and their interaction with waveguide modes has been discussed. The dependence of the shape of reflection coefficient at the resonant angle on the ratio between the real and imaginary parts of the dielectric constant of the first layer of the structure is analyzed. It is demonstrated that depending on the material, the shape of the curve can have a peak or deep minimum at resonant conditions. These effects can be used in intracavity laser selectors or highly sensitive sensors. Due to the significant field amplification in the last layer of the structure, it has been proposed to use in it a material with a nonlinear Kerr type response. A system of differential equations is derived to describe the dynamics of the dependence of the reflection coefficient on the intensity of the incident radiation at angles of incidence close to the resonance. The existence of bistability of the reflection coefficient is denoted. Polyvinylidene fluoride-based polymer was chosen as materials with cubic nonlinearity. The nonlinear optical properties of copolymer polyvinylidene fluoride with trifluoroethylene (P(VDF-TrFE)) and its interaction with ZnO nanoparticles when excited by single picosecond laser pulses at a wavelength of 1064 nm in a wide range of peak radiation intensities from 0.01 to 2000 GW/cm2 are investigated experimentally. Outlook for the use of copolymer P(VDF-TrFe) as a chemically stable and sensitive material is given. Due to its efficient nonlinear optical response, P(VDF-TrFE) is promising for use in optics, for example, as a sensor or ultra-fast light switch.