Generation of subnanosecond solitary pulses by backward stimulated Raman scattering in hydrogen-filled photonic crystal fibres

Here we report the observation of soliton-like pulses generated by BSRS in a gas-filled photonic crystal fiber (HC-PCF). The excellent performance of HC-PCF for SRS studies was shown recently in the quasi CW-regime. In the present experiment, we have observed high energy pulses of duration (0.7 ns) significantly shorter than the irreversible phase relaxation time T2 of the Raman transition. The fact that the pulse parameters (temporal shape, duration and energy) are insensitive to the temporal structure of the seed pulse (generated by forward SRS from noise) suggests that they are similar to solitary pulses generated in laser amplifiers.