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The objective of this work is to investigate the effect of nonlinearity-induced virtual gain in parabolic pulse (PP) formation by dispersion varying fibers and utilizing this gain over that of dispersion. As chalcogenides show high values of nonlinear coefficient, a dispersion decreasing fiber, named as nonlinearly tapered chalcogenide fiber (NLTCF), is designed here by optimizing different combinations of chalcogenide materials and core radius profiles such that efficient PP can be generated at considerably shorter optimum lengths with respect to the corresponding constant dispersion fiber. With suitable manoeuvring of the nonlinearity-induced virtual gain, a fiber combination consisting of a dispersion increasing fiber and the NLTCF shows enough efficiency to reduce the optimum length significantly. Although the virtual gain due to dispersion dominates over that due to nonlinearity in silica fibers, the situation is completely reversed in the case of specially designed highly nonlinear fibers. When compared to silica-based fibers, these types of fibers perform remarkably better in PP formation at shorter values of optimum fiber length with a higher amount percentage reduction of length making the higher order dispersive terms ineffective as well. [ABSTRACT FROM AUTHOR]

Normal dispersion decreasing fibers (NDDFs) employed for parabolic pulse (PP) generation are limited by the presence of inherent third-order dispersion (TOD), which leads to distortion in pulse shape from its parabolic nature. This necessitates a compensation method for TOD for such fibers. Dispersion-compensating fiber (DCF) amplifiers with relatively smaller values of dispersion can also be largely affected by this harmful effect of TOD when used for the same purpose. As a solution, a time-reversal system (TRS) based on a time-conjugating technique is employed with the aim of minimizing the deleterious effects of TOD. A detailed study on the estimation of the critical length where the time lens system needs to be implemented within the fiber link is crucial for reshaping the pulse into parabolic form. An NDDF is designed and optimized to possess a relatively higher value of TOD and a cascaded fiber optic system comprising the first stage of the proposed NDDF, the TRS and the second stage of the NDDF is suggested here to obtain linearly chirped PP at the output end even in the presence of a high value of TOD. The proposed scheme has also proved to be efficient for better pulse reshaping through DCFs possessing a high amount of TOD. [ABSTRACT FROM AUTHOR]