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In this paper, we report a simpler and efficient hybrid laser amplification system, which delivers a single pulse energy of 20 mJ at 500 Hz with a pulse width of 278 ps. This hybrid amplification system mainly consists of a hundred-picosecond all-fiber structure seeder, a regenerative amplifier and a single-pass amplifier. The hundred-picosecond laser pulse from the fiber seed is first amplified to 4 mJ by a regeneration amplifier with a normally doped Nd:YAG rod. For the improvement of the laser energy, the QCW side-pumped Nd:YAG single-pass amplifier has been adopted at the second stage of solid-state amplifiers. To reduce the serious thermal effect, the bonded composite YAG-Nd:YAG-YAG rod crystal is used as the gain medium, which possesses 6 mm in diameter and 85 mm in effective pumped length, and a doping concentration of 0.8%. Finally, 20 mJ output energy and 278 ps pulse duration are obtained with a peak power of 72 MW, and its beam quality factor is 1.7. In addition, this laser amplifier is confirmed by latter theoretical simulations of laser-induced plasma in silicon-based photodiode. The high-energy amplification of the hundred-picosecond pulse is realized in this hybrid amplifier system, which will be used as laser irradiation source in laser-induced damage application.
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