A multi-kW average power pulsed CO₂ laser system using master oscillator – Power amplifier scheme

A high power pulsed CO₂ laser system using master oscillator – power amplifier scheme (MΟΡΑ) has been studied and its output characteristics have been examined. A Q-switched CO₂ laser is used as a master oscillator and a high power continuous wave (CW) CO₂ laser rated at 14kW output power is used as a power amplifier. Average power of master oscillator can be varied from 0.1 to 0.5kW with a maximum pulse repetition frequency of 90kHz. A power amplifier consists of a positive branch unstable resonator with a 3mm-diameter hole at the center of a convex shaped cavity mirror. The pulsed laser beam from the master oscillator is focused and injected into the power amplifier through this hole. Output average power of 11.3 kW at 30kHz pulse repetition frequency is obtained. Pulse power modulation of 0 – 100% is observed and its temporal pulse shape is similar to that of Q-switched pulse containing initial spike and pulse tail.