Autor(es): Janeiro, Fernando M.
Data: 2010
Identificador Persistente: http://hdl.handle.net/10174/2008
Origem: Repositório Científico da Universidade de Évora
Assunto(s): Fiber Optics; Electromagnetic Propagation in Chiral Media; Semileaky Modes; Multi-channel Soliton Communication Systems; Dispersion Management in Optical Communication Systems; Relativistic Electrodynamics
This thesis addresses the effects of chirality and nonlinearity in fiber optics. Most photonic applications are based on conventional optical fibers in the linear regime. Although nonlinear effects in fiber optics have been extensively studied, that is not the case with chirality. In fact, the study of chirality in fiber optics is in its very early stages. Maxwell’s equations are unified with Einstein’s special theory of relativity through a tensor formulation of classical electrodynamics. Through the study of a moving dielectric medium the general concept of bianisotropic media is introduced. A modified Lorentz model, based on the dipole response of a single helix, is developed. This model is used to obtain the dispersion behavior of the constitutive parameters of chiral isotropic media (also known as optically active media). The study of propagation in a symmetric planar chirowaveguide naturally evolves into the analysis of the propagation characteristics of chiral optical fibers. Dispersion diagrams for guided modes, surface and semileaky, are presented. Radiation loss in semileaky modes is also analyzed. Semileaky modes in chirowaveguides are physically explained through the study of the reflection problem at a planar interface between chiral media. Propagation of solitary waves is studied in the framework of multichannel nonlinear optical communication systems with dispersion management. A Lagrangian formulation is developed in order to obtain optimal dispersion maps for both filtered and unfiltered optical communication systems. A good agreement between the results obtained using this variational approach and the Split-Step Fourier Method was found.
