Pulse splitting is a well-known process occurring in the very initial moments of pulse propagation in nonlinear optical fibers. According to the most accredited theory of pulse splitting [1], in the femtosecond regime, higher-order solitons are affected by stimulated Raman scattering and higher-order dispersion terms, becoming unstable and eventually breaking up into several fundamental solitons. However, this well-known description ignores some processes that could affect the soliton dynamics, such as interaction between solitons, and the emission of dispersive wave radiation near a zero group-velocity dispersion point. In a series of recent experiments [2] short and intense pulses have been launched in highly nonlinear photonic crystal fibers (PCFs). The unexpected formation of long-lived two-peak soliton states for specific magic input pulse energies was observed. Such soliton states were numerically discovered and studied in 1996 by Akhmediev et al. [3]. Inspired by the recent experimental observation of the Raman multi-peak states in [2] and by the early numerical findings in [3], we investigate the issue of Raman multi-peak states in detail [4,5].
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