The effect of hydrogen on the 585.3-nm helium-neon nuclear-pumped laser
The use of hydrogen as an admixture gas in the ($\sp3$He)$\sp4$He-Ne laser at the 2P$\sb1$-1S$\sb2,$ 585.3-nm Ne transition has been found to be more effective in depopulating the lower excited laser state, 1S$\sb2,$ than the use of heavy inert (noble) gases. Experimental results using the U of Illinois TRIGA reactor to pump this laser mixture at 585.3 nm feature the lowest threshold power density ever reported for visible nuclear-pumped, e-pumped and heavy ion beam-pumped lasers. The threshold neutron flux for the above transition was $1.5 \times 10\sp{13}$ n/(cm$\sp2$-sec), corresponding to threshold pumping power density 43 $\pm$ 2 mW/cm$\sp3.$ This is the second-lowest threshold power density observed for NPLs over all wavelengths, second only to the Soviet results on Ar-Xe infrared lasers (2.05 and 2.65 $\mu$m) that have a threshold power of $\sim20$ mW/cm$\sp3.$
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign