Arbitrary picosecond pulse shaping in a radially polarized Yb-fiber MOPA beyond 10 W

We demonstrate simultaneous spatial and arbitrary temporal pulse-shaping with a picosecond Yb-doped fiber laser system generating an output power > 10 W. By using a self-developed feed-back control algorithm on a single polarization optical pulse shaper, we obtained arbitrary complex pulse structures in the time domain with high accuracy and at high power level. Meanwhile, the pulse shaping in the spatial domain has been achieved using an in-house S-waveplate to change the linearly polarized fundamental mode into doughnut modes with different polarizations each at a time. This new capability enhances the versatility of ultrashort fiber laser systems for high precision material processing. Directly amplifying the radially polarized doughnut-mode avoids complex beam conversion at the output and provides an efficient route for power-scaling.