High-Energy Nanosecond Optical Vortex Output From Nd:YAG Amplifiers

Optical vortex amplification up to the joule level using flash-lamp-pumped Nd:YAG amplifiers has been demonstrated for the first time. In experiment, vortex seed pulses were converted from a conventional Q-switched Nd:YAG laser output by a spiral phase plate and amplified with two Nd:YAG amplifier stages. A maximum output energy of optical vortex up to 995 mJ has been achieved at 10 Hz in a 10-ns pulse, corresponding to an amplification factor of 295%. A maximum second-harmonic energy up to 470 mJ was generated from the amplified vortex output by using a KD*P crystal. The prospects of joule nanosecond vortex pulses generation by this approach were discussed.