A compact wide-aperture single-mode TE-CO2laser with a low chirp rate

Single mode operation of a TE-CO
2
laser was obtained using a
2 \times 2 \times 30
cm gain module in a Cassegrain resonator with a Gaussian reflectivity convex mirror to produce a fundamental mode of large cross sectional area, and reducing the pressure to 375 torr in a 50 cm long cavity to limit the oscillation to a single longitudinal mode. The 70 ns gain switched pulse (FWHM) had an energy of 175 mJ, a peak power of 2.0 MW, a diffraction limited far-field, and a frequency chirp rate lower than 60 kHz/μs
²
.