title: Fifty-ps Raman fiber laser with hybrid active-passive mode locking.
abstract: Actively mode locked Raman lasing in a ring PM-fiber cavity pumped by a linearly polarized Yb-doped fiber laser is studied. At co-propagating pumping, a stochastic pulse with duration defined by the AOM switching time (~15 ns) is generated with the round-trip period. At counter-propagating pumping, one or several sub-ns pulses (within the AOM switching envelope) are formed. It has been found that the formation of such stable multi-pulse structure is defined by the single-pulse energy limit (~20 nJ) set by the second-order Raman generation. Adding a NPE-based saturable absorber in the actively mode locked cavity, results in sufficient shortening of the generated pulses both in single- and multi-pulse regimes (down to 50 ps). A model is developed adequately describing the regimes.
authors.forename: A G
authors.initials: AG
authors.lastname: Kuznetsov
authors.forename: D S
authors.initials: DS
authors.lastname: Kharenko
authors.forename: E V
authors.initials: EV
authors.lastname: Podivilov
authors.forename: S A
authors.initials: SA
authors.lastname: Babin