Gain Performance of Radio Frequency-Excited Axial Fast-Flow CO2 Laser Amplifier
To achieve high power,short-pulse CO2 laser outputs,a 13.56 MHz radio frequency(RF)-excited axial fast-flow CO2 laser amplifier with an adjustable RF injection power of 0‒88 kW is developed in this study.Additionally,a laser-amplification experimental device is created to investigate the gain performance of the amplifier.First,the six-temperature model theory is described and the laser-amplification kinetic equation is established and its output characteristics are calculated.Second,the relationship between amplifier RF injection power,CO2 proportion,non-dissociation ratio,and other parameters and the small-signal gain coefficient under three different cavity pressures is analyzed.When the amplifier cavity pressure is 8 kPa,the RF injection power is 50 kW,and the CO2 ratio is 14%,the maximum small-signal gain coefficient is obtained.As the RF injection power continues to increase,the small-signal gain coefficient first increases and then gradually saturates.Reasons contributing to the amplifier-gain saturation are analyzed theoretically.Based on experimental measurements,when the seed light input power is 110 W,the amplifier output power can exceed 3500 W.Finally,the evolution of the laser-pulse waveform during the gain-extraction stage is simulated and the time-domain variation characteristics of the small-signal gain coefficient are analyzed.
amplifierhigh power CO2 lasersix-temperature modelsmall signal gain
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