Study on PT -Symmetric linear and nonlinear optical systems

Abstract

The significance of symmetry in unravelling the mysteries of nature cannot be overstated. In this dissertation, we delve into the intricate connections between the mathematical frameworks of quantum mechanics and electrodynamics, leveraging their underlying analogies. Through this exploration, we show that optics can provide a fertile ground for studying, observing, and utilizing symmetries. Specifically, our research focuses on exploring parity-time (PT) symmetry within the domain of classical optics. By investigating this intriguing symmetry within optics, we uncover novel insights that bridge the gap between theory and practice. This dissertation serves as a testament to the fruitful interplay between the conceptual realm of symmetries and the tangible applications within the realm of optics. The existence of PT-symmetry may lead to entirely real spectra in non-Hermitian systems. In the realm of optics, PT-symmetric structures involving balanced amount of gain and loss exhibit captivating traits that remain inaccessible within conventional Hermitian systems. In this study, we embark on a journey to harness the potential of PT-symmetric principles within optical domains. Our endeavours begin with designing and simulating optical switches, specifically focusing on their low power consumption attributes. Leveraging PT-symmetry in directional couplers and fiber Bragg gratings (FBGs), we unveil novel avenues for efficient switching functionality. These developments promise to advance the practicality and sustainability of optical switching technologies. Moreover, our investigations delve into the domain of microcavity resonators, explicitly exploring the concept of exceptional points (EPs). By perturbing the cladding index of a cavity, we harness the power of EPs to enhance the sensitivity of coupled three microcavity resonators. This intricate vii viii manipulation of cavity parameters offers new vistas for achieving heightened sensitivity in resonant systems. Other exciting phenomena also arise in PT-symmetric insulator-metal-insulator (IMI) structure. Along these lines, we introduce a new class of excited surface plasmon polaritons (SPPs). This innovation affords a directional control over the propagation of SPPs, opening doors to directional switching possibilities. Finally, our inquiry takes looks at adiabatically coupled PT-symmetric three waveguides directional coupler, delving into their switching characteristics in the presence of various nonlinear configurations of waveguides.