A train of backward Raman soliton pulses in hollow-core photonic crystal fibres filled with hydrogen gas

By using a novel hollow-core photonic crystal fibres (HC-PCFs) filled with hydrogen gas, the like-solitary pulse train in backward stimulated Raman scattering (BSRS) is experimentally reported. The pulse dynamics go through two processes. At first, the seed pulse amplification is uniform at relatively low pump energy. Secondly, at high pump energy, the seed one becomes amplifying and resharpenening to a train of successive solitons with secant-hyperbolic shapes. The asymptotic solution for BSRS equations is also used to explain qualitatively for these interesting phenomena in a transient regime.