100W, single mode, single polarization, picosecond, ytterbium doped fibre MOPA frequency doubled to 530 nm

High average power laser sources operating in the picosecond (ps) regime are useful for a wide range of applications including frequency-doubling and pumping of OPOs. Gain switching (GS) of laser diodes provides a practical and low cost method to generate ps pulses at GHz repetition rates and mW average power levels. Such devices represent excellent seeds for high power fiber MOPAs allowing power scaling to the 100 W regime and we recently reported average powers in excess of 300 W from a 1060 nm gain-switched FP laser seeded ytterbium doped fiber amplifier (YDFA) MOPA. However this system incorporated free space pump and signal coupling greatly compromising the practicality of the system. Moreover, the output polarization was ill-defined limiting the utility of the system for many frequency conversion applications. The authors present a fiberised, diode-seeded, YDFA MOPA system generating linearly polarized, diffraction-limited, 20ps pulses at repetition rates ranging from 113.5 MHz to 908 MHz and at average output powers in excess of 100W. This system represents a considerable improvement in practicality and performance relative to previous high power, fiber-based ps pulse sources. The output of the MOPA was launched into an LBO crystal to generate 45 W of green light.