Tunable Long Pulse UV-preionized TE CO₂ Laser With Pulser/sustainer Discharge

Long pulse TE CO₂ lasers can be found applications in the fields as laser machining,laser radar(Ladar/lidar), laser propulsion, opto-electronic countermeasures, and so on.In this paper the tunable characteristics of a grating tuned long pulse UV-preionizedTE CO₂ laserexcited by Pulser/sustainer discharge with an active volume of 1.17Lare investigated experimentally.First, with gas mixture of CO₂:N₂:He=1:5:19, the tunable characteristics of threegrating with the different grating parameters of 80 line/mm,120 line/mm,150 line/mm are investigated respectively under different gas pressure and dischargevoltage. With the 120 line/mm grating resonator, altogether 75 spectral lines are obtained andthe laser output energies of the four spectral lines 9R(20), 9P(20), 10R(20) and 10P(20) arecomparable to that of a conventional non-resonant cavity.Then with the grating t of 120 line/mm, the tunable characteristics oft he laser underdifferent discharge voltage, discharge pulse width, gas mixture and gas pressure areinvestigated. Detailed measurements are carefully made on the output laser energiesand laser pulse widths of the four spectral lines 9R(20), 9P(20), 10R(20) and 10P(20)under different discharge voltage, discharge pulse width, gas mixture or gas pressure.The measured results strongly illustrate that the laser pulse width in a tunable longpulse TE CO₂ laser with Pulser/sustainer discharge varies with the output laserwavelength. By simultaneously measuring the discharge current waveform and theoutput laser pulse profile, it is found that the variation of the laser pulse width at eachspectral line is perhaps mainly due to the gain difference of each spectral line.