Coherent hyper-Raman scattering by autoionization states of atoms excited in the plasma of an electric discharge

The possibility of realizing an efficient gaseous laser-beam-generating medium that utilizes $\ensuremath{\Lambda}$-type 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. Specifically, it is investigated if multiphoton stimulated hyper-Raman scattering (SHRS) processes driven by fluorescence radiation generated in a continuous electrical discharge present within the vapor-containing cell could produce continuous-wave (cw) optical gain at the $\ensuremath{\Lambda}$-atom resonance frequencies ${\ensuremath{\omega}}_{o}$ and ${\ensuremath{\omega}}_{o}^{\ensuremath{'}}$. It is deduced that such gain could result from $n$ -photon $(n\ensuremath{\geqslant}4)$ SHRS processes only if absorption of fluorescence pump light occurs in the first three transitions of the $n$ -photon sequence representing the process unit step. Estimates of the amount of optical gain that could be produced in such a system indicate that it should be sufficient to allow multiwatt cw laser operation to occur on one set of $\ensuremath{\Lambda}$ transitions connecting levels in a ``double-$\ensuremath{\Lambda}$'' structure, with the pump light being discharge-produced fluorescence centered about the transitions of the other $\ensuremath{\Lambda}$ pair. However, to initiate operation of such a device would require injection into the laser optical cavity of intense ``starter'' laser pulses at both lasing frequencies. What should be an optimal experimental configuration for determining feasibility of the proposed laser device is described. In the suggested configuration, Cs-atom $6{S}_{1∕2}\text{\ensuremath{-}}6{P}_{1∕2}$ transitions form the double-$\ensuremath{\Lambda}$ structure.The possibility of realizing an efficient gaseous laser-beam-generating medium that utilizes $\ensuremath{\Lambda}$-type 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. Specifically, it is investigated if multiphoton stimulated hyper-Raman scattering (SHRS) processes driven by fluorescence radiation generated in a continuous electrical discharge present within the vapor-containing cell could produce continuous-wave (cw) optical gain at the $\ensuremath{\Lambda}$-atom resonance frequencies ${\ensuremath{\omega}}_{o}$ and ${\ensuremath{\omega}}_{o}^{\ensuremath{'}}$. It is deduced that such gain could result from $n$-photon $(n\ensuremath{\geqslant}4)$ SHRS processes only if absorption of fluorescence pump light occurs in the first three transitions of the $n$-photon sequence representing the process unit step. Estimates of the amount of optical gain that could be produced in such a system indicate that it should be sufficient to allow multiwatt cw laser operation to occur on one set of $\ensuremath{\Lambda}$ transitions connecting levels in a ``double-$\ensuremath{\Lambda}$'' structure, with the pump light being discharge-produced fluorescence centered about the transitions of the other $\ensuremath{\Lambda}$ pair. However, to initiate operation of such a device would require injection into the laser optical cavity of intense ``starter'' laser pulses at both lasing frequencies. What should be an optimal experimental configuration for determining feasibility of the proposed laser device is described. In the suggested configuration, Cs-atom $6{S}_{1∕2}\text{\ensuremath{-}}6{P}_{1∕2}$ transitions form the double-$\ensuremath{\Lambda}$ structure.

Physical Review AMay 12, 20050 citations

n

-photon $(n\ensuremath{\geqslant}4)$ SHRS processes only if absorption of fluorescence pump light occurs in the first three transitions of the

n

-photon sequence representing the process unit step. Estimates of the amount of optical gain that could be produced in such a system indicate that it should be sufficient to allow multiwatt cw laser operation to occur on one set of $\ensuremath{\Lambda}$ transitions connecting levels in a ``double-$\ensuremath{\Lambda}$'' structure, with the pump light being discharge-produced fluorescence centered about the transitions of the other $\ensuremath{\Lambda}$ pair. However, to initiate operation of such a device would require injection into the laser optical cavity of intense ``starter'' laser pulses at both lasing frequencies. What should be an optimal experimental configuration for determining feasibility of the proposed laser device is described. In the suggested configuration, Cs-atom $6{S}_{1∕2}\text{\ensuremath{-}}6{P}_{1∕2}$ transitions form the double-$\ensuremath{\Lambda}$ structure.