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Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Light gain without the population inversion due to the level dependence of collision cross sections

Jing-Yong Ye, Ming-Shing Zhan, Shikang Zhou

Published Oct 28, 1992• 0 citations
Publisher

Abstract

Based on the different changes of the velocity distributions of the ground and excited levels due to the level dependence of collision cross sections in a flowing system, a new mechanism for the light amplification without population inversion is presented.
DOI
10.1117/12.130481

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The optogalvanic effect induced in a Hg-Ar discharge by light at 546.1 nm is studied experimentally and theoretically. The plasma and its response to a disturbance in the atomic-level populations are described entirely in terms of electron collision cross sections and other fundamental parameters. In a detailed description of the laser interaction with the atomic system, it was necessary to take into account velocity-changing collisions (VCC). These collisions (VCC) strongly modify the interaction between the Doppler-broadened system and the optical field. In some Doppler-free optogalvanic spectra the dramatic influence of VCC on the velocity distribution of atomic-level population is evident. Measurements of the magnitude of the optogalvanic signal confirm most of the theoretical results. Some anomalous features of the impedance change due to a weak beam were observed when a strong counterpropagating beam was introduced.