Optics and Nonlinearities of Excitons in Organic Multilayered Nanostructures and Superlattices

Abstract

This chapter discusses optics and nonlinearities of excitons in organic multilayered nanostructures and superlattices. Superlattices help study the phenomena that arise at interfaces among different media. These artificial layered crystals may be considered systems with condensed interfaces because the total area of their interfaces is proportional to the volume of a system. Under these conditions, some specific surface and quasi-two-dimensional effects make important contributions to bulk crystal optics. For example, their macroscopic electrodynamics correspond to uniaxial rather than isotropic crystal optics. Different interactions taking place at interfaces are important and can be responsible for the appearance of new linear and nonlinear optical effects. Thus, it can be shown that in such crystalline layered molecular structures, excitations can be concentrated near the interfaces among different layers. Various types of Fermi resonances can be used as a universal means for achieving optical bistability and multistability. New states, Fermi-resonance-interface modes, and Fermi-resonance-interface solitons are described in the chapter. Fermi resonance is a phenomenon that takes place in vibrational or electronic spectra of molecules. Interesting phenomena can take place in systems with Fermi resonance under the influence of an external electromagnetic field. The chapter presents an example of bistable energy transmission through an interface with a Fermi-resonance interaction.