Emission characteristics of a pulsed CO2 laser with a self-filtering unstable resonator under conditions of a strong self-interaction of radiation in the active medium. I. Theoretical analysis

A theoretical analysis is made of the space and time characteristics of the radiation emitted by an electron-beam-controlled pulsed CO₂ laser with a self-filtering unstable resonator capable of ensuring a divergence close to the diffraction limit in the case of systems with a high optical quality of the active medium. It is shown that when the pump power is limited, the effects of the thermal self-interaction in a resonator sometimes result in 100% modulation of the output signal, but the divergence of the radiation still remains close to the diffraction limit.