Generation of 200 fs optical vortex pulses with 12 MW peak power from a Yb-doped fiber amplifier

We report the generation of high peak power linearly polarized femtosecond optical vortex pulses based on parabolic pulse amplification within a large-mode-area few-mode Yb-doped fiber (YDF) amplifier system. A dispersion-managed passively mode-locked Yb-doped fiber oscillator with a Gaussian-shaped spectrum serves as the seed source, which evolves into parabolic shape in the subsequent preamplifiers. A <i>q</i>-plate-based mode converter, positioned before the power amplifier, is employed to convert the Gaussian-shaped beam into optical vortex beams with a topological charge of <i>l </i>= ±1. The resulting optical vortex beams are efficiently amplified to an average output power of ∼16.8 W at a repetition rate of 3.7 MHz, corresponding to a pulse energy of 4.5 µJ. The chirped output pulses are externally compressed to ∼200 fs, achieving a peak power of ∼12.7 MW. To the best of our knowledge, this represents the highest peak power achieved to date for optical vortex pulses generated from a conventional step-index fiber.