Control of laser pulse waveform in longitudinally excited CO2 laser by adjustment of gas medium

Abstract

In a longitudinally excited CO2 laser that had a 45 cm-long discharge tube and a fast discharge circuit, we investigated control of the laser pulse waveform by adjusting the gas medium. In a longitudinal discharge at a low pressure of 10 kPa or less, the laser pulse waveform dramatically changed with the gas pressure and the mixing ratio due to the changing discharge formation time, which varied from 57 ns to 262 μs. A low-pressure (<2 kPa) CO2-rich gas produced a tail-free short laser pulse with a width of about 100 ns. A high-pressure (<2 kPa) CO2-rich gas and a low-pressure (<6 kPa) N2- rich gas produced a short laser pulse containing a spike pulse with a width of about 100 ns and a pulse tail with a length of 10−200 μs. A high-pressure (<6 kPa) N2-rich gas produced a long laser pulse with a pulse width of 10−20 μs. Therefore, the laser pulse waveform of the longitudinally excited CO2 laser could be controlled.