1 kHz, 280 mJ, 14.5 ns High-power and High-energy 2.05-μm Laser Generation via a Three-stage Ho:YLF Rod Amplifier

A 2.05-μm Ho:YLF MOPA system with both high average power and high pulse energy operating at 1-kHz repetition rate is demonstrated, achieving a maximum output power of 280 W with a pulse width of 14.5 ns. The system comprises three-stage amplifiers, boosting a 20-W seed laser to output powers of 110 W, 205 W, and 280 W, corresponding to extraction efficiencies of 46.1%, 45.0%, and 34.9%, respectively. At maximum output, the system exhibits excellent beam quality (Mx2 = 1.22 and My2 = 1.23) and power stability (RMS = 0.5% over 30 min). To the best of our knowledge, this work reports the highest pulse energy (280 mJ) achieved for a 2-μm laser operating at a kHz repetition rate. Additionally, a slice model of an end-pumped quasi-three-level laser amplifier was developed to analyze the output limitations of multi-stage Ho:YLF amplifiers based on rod geometry, providing theoretical support for the experimental results.