Abstract:
A repetitive pulsed CO
2 laser with variable pulse widths and tunable wavelengths was developed and the photon number change behavior inside the resonant cavity which has an inserted Ge crys- tal acousto-optical modulation was researched on both theory and experiment. The experimental results show that acousto-optical modulation theory is not suit to explain output characteristic of the laser pulses, the felicitous description should make use of the Q switched rate equation instead of, due to the reason that the action of switched gain effect produced from laser level population inversion transition is much larger than that of the transit-time along the acousto-optical crystal. When the Ge crystal is added with controlled radio frequency modulation signals, the laser can realize laser pulses with a range from nanosecond to microsecond under the conditions of 3 - 8 W average power and 1 Hz - 100 kHz repetition rate, corresponding the maximumpulse power 10 kW. Over 30 laser spectral lines between 9.2 - 10.8
m can be achieved if the metal grating is used for substituting the cavity output coupler.