Archive | 2019
Numerical modeling and simulations on splitting of chirped optical pulses in heavily doped thulium fiber amplifiers through modal instability analysis
Abstract
In this paper, mathematical model and simulations displaying the phenomenon of modal instability (MI) in 1050 nm pumped heavily doped Thulium (Tm3+) fiber amplifier is presented. Pulse splitting effect through MI with variation in chirp parameter and non-linear fiber length was modeled and simulated. The pulses considered were sech, Gaussian, and super-Gaussian type. Model was computationally solved on MatLab and the results were verified by incorporating similar conditions and parameters on OptiSystem 16 simulation platform. Results concludes the optimum non linear length (LNL) and the chirp parameter (C = 12) which has to be taken so as to obtain continues time domain pulse train as well as linearly spaced frequency combs. The repetition rate of 500 MHz for 4 ps pulse at 1460 nm with peak sub-pulse energy of 8 nJ was obtained and has been reported to the first time (under MI mechanism) to the authors knowledge. Optimum TDFA length was concluded as 375 m at which MI phenomenon was triggered.