Self-mixing detection of backscattered radiation in single-mode pulse-periodic CO2 lasers.
The self-mixing (autodyne) effect in single-mode CO(2) lasers with pulse-periodic (PP) pumping of the active medium is theoretically analyzed and experimentally investigated. A semiempirical model of the autodyne effect in CO(2) lasers of this type is developed that allows the laser beat signal to be described from the known shape of the generated pulses. The self-mixing effect in PP CO(2) lasers is shown to be identical with that in continuous-wave CO(2) lasers, except that the autodyne amplification during the laser pulse proves time-dependent. It is demonstrated that the amplitude-frequency characteristic of the autodyne amplification for PP CO(2) lasers is also of resonance nature, but its bandwidth is broadened, as compared with that in the case of continuous laser pumping. As in the case of continuous pumping, the self-mixing effect in PP CO(2) lasers can be used to detect and analyze backscattered signals, specifically for measuring the rates of destruction of materials by the 10 μm radiation and for monitoring this process.
Institute on Laser Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region, Russia. Alexey.Konovalov@ilitras.troitsk.ru
Alexey N
AN
Konovalov
Valerii A
VA
Ul'yanov