W. Viol et J. Uhlenbusch, GENERATION OF CO2-LASER PULSES BY Q-SWITCHING AND CAVITY DUMPING AND THEIR AMPLIFICATION BY A MICROWAVE EXCITED CO2-LASER, Journal of physics. D, Applied physics, 29(1), 1996, pp. 57-67
Q-switched low-pressure CO2 lasers allow both the production of maximu
m laser pulse power and high average laser power at high pulse repetit
ion rates. A Q-switched CO2 laser oscillator amplifier system consisti
ng of a DC discharged, wavelength tunable and diffusion cooled oscilla
tor and a microwave excited amplifier is described. By mechanical Q-sw
itching of the oscillator laser pulses with a pulse repetition rate of
4-200 kHz and TEM(00) beam quality can be produced. After the amplifi
cation the peak power reaches 0.9 MW at a pulse repetition rate of 10
kHz and 0.2 MW at a 100 kHz repetition rate. The pulse duration (FWHM)
is about 0.2 mu s. The maximum average power of 7 kW in the Q-switche
d mode reaches nearly the maximum cw laser power of 10 kW (with TEM(00
) beam quality). The laser pulse duration can be shortened by the comb
ination of cavity dumping and electro-optical Q-switching. This pulsed
operation leads to laser pulses with 35 ns pulse duration and 1.9 MW
maximum power at a pulse repetition rate of 10 kHz and an average lase
r power of 0.8 kW. The self-oscillation of the oscillator amplifier sy
stem can be suppressed by an optical shutter between oscillator and am
plifier. The laser beam power can be calculated by a six-temperature m
odel including rotational relaxation, intramode and intermode vibratio
nal energy exchange.