Chemically induced processes evidencing Raman gain

David R. Grantier; Peter M. Medley; James L. Gole

doi:10.1117/12.204961

31 March 1995 Chemically induced processes evidencing Raman gain

David R. Grantier, Peter M. Medley, James L. Gole

Proceedings Volume 2502, Gas Flow and Chemical Lasers: Tenth International Symposium; (1995) https://doi.org/10.1117/12.204961
Event: Gas Flow and Chemical Lasers: Tenth International Symposium, 1994, Friedrichshafen, Germany

Abstract

The highly selective Na₃ + X (Cl,Br,I) reactions have been shown to create a continuous electronic population inversion based on the chemical pumping of Na₂. Optical gain through stimulated emission has been demonstrated in regions close to 527, 492, and 460 nm ((alpha) equals 8 X 10^-3 cm^-1 for an individual rotational level at -527 nm). A device has ben constructed with a focus to increasing amplifier gain length and amplifying medium concentration based on the controlled intersection of supersonically expanded sodium and halogen atom sheaths. The interaction forms an extended reaction-amplification zone centered on-axis in an optical cavity, thus facilitating the conversion of the observed amplifiers to chemical laser oscillators. Initial results with this upscaled device, where the sodium metal expanded in both pure and seeded supersonic expansion is intersected by a bromine atom flow, provide the first example of chemically enhanced Raman scattering. Unique Raman signals are induced by and correlate with emission from the Na D-line components formed in the chemical reaction zone primarily as a result of Na₂ + Br yields Na^* + NaBr reaction, cannot be readily generated by light scattering due to an external light source, and appear to be enhanced by the environment of the reaction zone itself. The Na D-line emitters interact with cooled sodium dimers in a resonance Raman scattering process, for which computer simulations suggest a scattering linewidth, (Gamma) -4 cm^-1. These results suggest an unusually fast resonance Raman scattering process which appears to be chemically enhanced. The results of initial double pass gain measurements suggest that a stimulated Raman process, similar to that associated with optically pumped alkali dimer lasers, has been observed.

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David R. Grantier, Peter M. Medley, and James L. Gole "Chemically induced processes evidencing Raman gain", Proc. SPIE 2502, Gas Flow and Chemical Lasers: Tenth International Symposium, (31 March 1995); https://doi.org/10.1117/12.204961

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