MW peak-power, mJ pulse energy, multi-kHz repetition rate pulses from Yb-doped fiber amplifiers

摘要

We report on pulsed fiber-based sources generating high peak and average powers in beams of excellent spectral/spatial quality. In the first setup, a ～10-kHz pulse repetition rate (PRR), 1ns-pulse, Q-switched microlaser seeded a dual-stage amplifier featuring a 40-μm-core Yb-doped photonic-crystal fiber (PCF) as the power amplifier. From this amplifier, we obtained diffraction-limited (M~2 = 1.05), ～ 1ns pulses of 1.1 mJ energy, ～ 1.1MW peak power, ～ 10.2W average-power, spectral linewidth ～ 9GHz, negligible nonlinearities, and slope efficiency > 73%. In the second setup, we replaced the seed source with a shorter-pulse (< 500ps) microchip laser of PRR ～ 13.4 kHz and obtained diffraction-limited (M~2 = 1.05), ～450ps pulses of energy > 0.7mJ, peak power in excess of 1.5 MW, average power ～ 9.5W, spectral linewidth < 35 GHz. To show further power scaling, these pulses were amplified in a 140-μm core Yb-doped fiber, which yielded multimode (M~2 ～ 9), 2.2mJ-energy, 30-W average-power pulses of peak power in excess of 4.5MW, the highest ever obtained in a fiber source, to our knowledge. In the third setup, an Yb-doped, 70 μm-core, intrinsically single-mode photonic-crystal rod was used to generate diffraction-limited (M~2 ? 1.1), ～ 10kHz PRR, ～ 1ns pulses of 2.05mJ energy, > 2 MW peak-power (the highest ever reported in a diffraction-limited fiber source), ～ 20W average-power, ～ 13 GHz spectral linewidth, and spectral signal-to-noise ratio > 50 dB. Finally, a single-polarization large-core Yb-doped PCF was used to demonstrate high-peak-power harmonic generation. We obtained ～ 1ns pulses of peak powers > 410 kW in the green (531nm) and > 190kW in the UV (265.5 nm).