Multifaceted dynamics of optical waves in linear and nonlinear pt symmetric fiber bragg gratings

Abstract

From the invention of mirrors to optical fibers, the quest to alter light propagation in a medium seems to be an unceasing one. At present, the field of refractive index engineering has witnessed one of its major milestones in the form of introducing non-Hermitian notions into the traditional optical structures. The advancements in the current optical technologies fetch one more degree of freedom to engineer the nature of light propagation in an optical system by taking advantage of the interaction among the refractive index, intrinsic loss, and the extrinsic gain of the system. Such an interplay is feasible only if the refractive index of the medium is assumed to be a complex entity rather than real. In particular, invoking the notion of Parity and Time (PT)-symmetry in any conventional optical systems is itself a new physics, as it leads to novel non-Hermitian structures that are supposed to be a trending topic in optics nowadays. newlineAmong the different PT-symmetric systems, this thesis deals with the study of linear and nonlinear dynamics of optical waves in some uniform and non-uniform PT-symmetric fiber Bragg gratings (PTFBGs). Specifically, the thesis deals with the linear dynamics of chirped, apodized, phase-shifted, and superstructure gratings with gain and loss. The extensive study on the spectral characteristics of these systems is motivated by the fact that these devices give rise to many peculiar features such as the light launching direction-dependent spectral response, lasing behavior, and reflection-less wave transport. In general, any of these PTFBG configurations can be readily built by having alternate regions of gain and loss in such a way that the real and imaginary parts of refractive index modulation are even and odd function of position, respectively. newline