Abstract
High-pressure CO2 lasers are capable of producing intense beams with continuous frequency tunability in the 9µm and 10µm bands. The linewidth, however, amounts in general to several GHz with multilongitudinal-mode oscillations.1 Although injection locking is widely applied to narrow the linewidth in various lasers, this technique is effective only at the wavelength near the line centers in the high-pressure CO2 lasers because of the lack of a suitable master oscillator for providing tunable injection beams.