1 MW Peak Power Tapered Fiber Amplifier of Picosecond Pulses Operated near 1030 nm

Inthe present work, the tapered Yb-doped fiber amplifier was optimized for operation in the spectral range near 1030 nm. Stimulated Raman scattering and four-wave mixing were nonlinear effects that limited the power scaling. We determined a superior gain regime, taper configuration, and pump injection condition to maximize the threshold of these nonlinear effects. As a result, we obtained two operating regimes: 13 ps pulses were amplified to 670 kW peak and 39 W average power in the first case, and to 1 MW peak and 13.8 MW average power in the second case. The fraction of unwanted components in the output spectrum did not exceed 2.5%, and the beam quality was almost diffraction-limited $\left(\mathrm{M}^{2}\lt 1.2\right)$.