Acoustic vibrations in a continuous-flow CO2 laser with an unstable resonator

A theoretical investigation is made of the growth of acoustic vibrations in the active gas stream of a CO₂ laser with an unstable resonator. The heat release associated with a perturbation of the light intensity accompanying the influence of an acoustic wave on the lasing conditions in the unstable resonator leads to modulation of the radiation. An analysis is made of the dependences of the instability growth rates on the parameters of the laser system. The threshold conditions and the growth rate of the acoustic vibrations are determined.