Generation of 13.9 µm radiation from CO2 by cascade lasing or externally applied CO2 laser

13.9 µm radiation from the 1000-0110 transition can be obtained from a CO2 laser by saturating the 0001-1000, 10.6 µm transition with an internally generated q-switched pulse or by the application of an external 10.6 µm pulse. Because of Fermi resonance between the symmetric stretch and the bending modes, decay of population from the 1000 level is fast, and such lasers operate at low power and energies. A theoretical model was developed to study such lasers. The results of the calculations indicate that a large-aperture E-beam-sustained discharge is effective for excitation of the cryogenically cooled gain medium, which uses He rich mixture at low pressure. The system is scalable and capable of generating large powers and energies.