Characteristics of a Q-switched CO2laser

The pulse width of a Q-switched CO2-N2-He laser operating at 10.6µ has been directly measured with a Au:Ge (77°) detector to be less than or equal to 25 nanoseconds. For a 3 meter CW CO2laser operating at low pressure the beat frequency between two longitudinal modes has been observed using the fast Ge:Au detector. When the laser transitions are pressure broadened, the laser tends to operate in a single mode. During Q-switched operation at 10.6µ, two new groups of laser oscillations have been detected at 4.35µ which arise from transitions between the 00°2-00°1 CO2levels. The first group of 4.35µ lines, which have an energy level in common with the 10.6µ transitions, occur following the 10.6µ pulse in a time short with respect to rotational equilibration; the second group, however, have no level in common with the 10.6µ transition and occur following the 10.6µ pulse in a time of the order of several rotational state lifetimes. Detailed assignment of all the 4.5µ lines is presently being made.