Discharge-Pumped Phasers

The possibility of realizing an efficient gaseous laser-beam-generating medium that utilizes coherently phased (i.e. "dressed") atoms for the active laser species, but that does not inherently require the use of external laser beams for pumping, is explored. From dressed-atom energy level diagrams, it is immediately apparent that continuous-wave (CW) optical gain at the two resonance frequencies of coherently phased atoms can only result when such atoms are additionally excited via nonlinear photonic processes. Non-parametric excitation processes of this type are considered - specifically, multi-photon stimulated hyper-Raman scattering (SHRS) processes driven by fluorescence radiation generated in a continuous electrical discharge present within the vapor cell. It is shown that no CW gain could result from dressed-atom excitation occurring via three-photon SHRS under any circumstances. Four-photon SHRS is a conceptually possible pumping means for such a device, and rough calculations indicate that the amount of optical gain produced by this high-order process should be marginally sufficient to allow multiwatt CW laser operation to occur on atomic transitions with levels relatively positioned to form a "double-" structure. However, to initiate operation of such a device would require injection into the laser optical cavity of an intense "starter" laser pulse. An experimental configuration is described for determining feasibility of the proposed laser device. In the suggested configuration, Cs-atom transitions form the double- structure.