1-mJ multi-kHz nanosecond pulses from a single-crystal Yb:LiLuF4 amplifier seeded by a passively-Q-switched laser

Single-crystal fiber Yb-doped LiLuF4 grown by the micro-pulling-down method was tested in a high-power pumped amplifier setup seeded by a passively Q-switched Yb:YLF laser. With 82-W absorbed pump power and 130-μJ injected pulse energy, the amplifier yielded 1.05-mJ pulses with 110-ns duration at 5.2 kHz, linearly polarized with excellent beam quality. These results prove the high optical quality and promising performance of this new material technology exploiting birefringent Yb-doped materials at very high pump power.