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

Abstract A 2.05 μm holmium-doped yttrium lithium fluoride (Ho:YLF) master oscillator power amplifier system with both high average power and high pulse energy operating at a 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, 205 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 ( M x 2 = 1.22 and M y 2 = 1.23) and power stability (root mean square = 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. In addition, 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.