High-Gain Nanosecond Vortex Laser

We demonstrate a high-gain vortex power amplifier with the double-pass configuration based on the rod Nd:YAG crystal. In the experiments, a nanosecond vortex seed beam is converted from a conventional Q-switched Nd:YAG laser output with a spiral phase plate and then amplified with the Nd:YAG amplifier stage. A maximum amplification output energy up to 163.5 mJ is achieved at 20 Hz with a 3.2-ns pulse, corresponding to an amplification factor of 81.8. Further discussions are provided to find ways of increasing the power scaling.