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Observation of undamped pulsations in a low-pressure, far-infrared laser and comparison with a simple theoretical model

par Abraham, Neal B.;Dangoisse, Didier;Glorieux, Pierre;Mandel, Paul
Référence Journal of the Optical Society of America. B, Optical physics, 2, 1, page (23-34)
Publication Publié, 1985

Article révisé par les pairs

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Résumé :

Experimental details of undamped pulsations are presented for a low pressure, far-infrared (FIR) laser optically pumped by a single-frequency CO2 laser in a standing-wave configuration for both the pumping and the FIR lasing action. Spontaneous pulsing in the single-mode HCOOH FIR laser at 742 /im was observed when the cavity was tuned to the FIR resonance and when the CO2 laser of high intensity was sufficiently detuned from the resonance of the pump transition to excite two distinct velocity groups of molecules to contribute to the FIR gain. Theoretical results, based on studies of a model for a laser with two distinct resonant species forming the gain medium, providea basis for understanding the origin of these instabilities. The model compares satisfactorily with the observed FIR instabilities including the variations in pulsing frequencies observed experimentally as the CO2 laser is detuned. Additional predictions from the model include details of transitions from cw to pulsing behavior and thresholds fr deterministic chaos that may be tested in future experiments. © 1985 Optical Society of America.