| Popis: |
We investigated the fundamental question of how electromagnetic waves propagate in an important class of inhomogeneousmetamaterials, with material properties gradually changing from positive to negative values ( transition metamaterials ). We discovered strongly polarization sensitive anomalous field enhancement near the zero refractive index point under oblique incidence of the wave on a realistic, lossy transition metamaterial layer potentially enabling a variety of applications in microwave, terahertz, and optical metamaterials, including subwavelength transmission and low-intensity nonlinear optical devices. We developed a generalized analytical model and solutions for nonlinear wave propagation in waveguide couplers with opposite signs of the linear refractive index, non-zero phase mismatch between the channels, and arbitrary nonlinear coefficients. These results offer a practical tool for designing novel metamaterials based couplers based on either double-negative or strongly anisotropic metamaterials that are likely to enable ultra-compact optical strorage and memory components for photonics on a chip applications. We proposed and investigated in detail a structure consisting of a nonlinear core with focusing or de-focusing Kerr nonlinearity and graded-index shell designed using transformation optics that can be switched from a concentrator squeezing light into the core to a variable focus lens by varying the intensity of incident light. As an extension of this project, we performed preliminary studies of the wave and ray properties of electromagnetic wave interactions in two-dimensional microcavities that contain a combination of PIM and NIM with negative dielectric permittivity and magnetic permeability. These studies indicate that NIM-PIM disk resonators can be specifically designed to emit intense radiation in a controlled manner. |
