Prospective use of a normally dispersive step-index chalcogenide fiber in nonlinear pulse reshaping

In this work, several normally dispersive highly nonlinear chalcogenide optical fibers (NDHNCFs) with a step-index profile have been designed and optimized in view of efficient parabolic pulse (PP) generation. A typical NDHNCF is selected such that the group velocity dispersion is highest among them and the corresponding nonlinearity is also very high. The input pulse parameters are optimized to find the lowest possible optimum length (L_opt) of the fiber where the linearly chirped PP is obtained. Further, it is found that for a shorter input pulse width, PP can be generated at a sufficiently smaller length of the NDHNCF with a slight compromise for its misfit parameter. A detailed analysis of the effect of pre-chirping helps to identify the suitable amount of initial chirp for different chalcogenide fibers with a choice of input pulse parameters. Although no improvement in PP generation is found for normal and initially chirped hyperbolic secant pulses, a highly efficient triangular pulse is achieved for a particular value of input pulse energy and the initial chirp parameter. Finally, the comparative study substantiates that our optimized NDHNCF is capable enough to generate quality PP at a length almost 70% shorter than a standard silica-based fiber.