According to several recent studies, the width of the sharp zero-phonon lines in the electronic spectra of impurities in solids, such as the $R$ lines of ruby, is due to Raman scattering of phonons by the impurity ions. The question whether such zero-phonon lines are homogeneously broadened is an important one, both for its own interest and for optical-maser applications. From a detailed study of the stimulated-emission spectra of a ruby laser operating in the traveling-wave modes, we obtain conclusive evidence that such zero-phonon lines are homogeneously broadened. Because the ${R}_{1}$ line of ruby is essentially homogeneously broadened at room temperature, the traveling-wave laser oscillates for all practical purposes only in a single mode. The spectral width of the laser emission is extremely sharp. It is less than 0.005 ${\mathrm{cm}}^{\ensuremath{-}1}$ at room temperature as compared to a width of the order of 1 ${\mathrm{cm}}^{\ensuremath{-}1}$ for conventional ruby lasers of comparable intensity. In addition, the output intensity no longer shows random spikes but shows a predictable train of regularly spaced spikes which agree well with theory.According to several recent studies, the width of the sharp zero-phonon lines in the electronic spectra of impurities in solids, such as the $R$ lines of ruby, is due to Raman scattering of phonons by the impurity ions. The question whether such zero-phonon lines are homogeneously broadened is an important one, both for its own interest and for optical-maser applications. From a detailed study of the stimulated-emission spectra of a ruby laser operating in the traveling-wave modes, we obtain conclusive evidence that such zero-phonon lines are homogeneously broadened. Because the ${R}_{1}$ line of ruby is essentially homogeneously broadened at room temperature, the traveling-wave laser oscillates for all practical purposes only in a single mode. The spectral width of the laser emission is extremely sharp. It is less than 0.005 ${\mathrm{cm}}^{\ensuremath{-}1}$ at room temperature as compared to a width of the order of 1 ${\mathrm{cm}}^{\ensuremath{-}1}$ for conventional ruby lasers of comparable intensity. In addition, the output intensity no longer shows random spikes but shows a predictable train of regularly spaced spikes which agree well with theory.

Physical ReviewOct 5, 196453 citations

Numerical studies of optical dephasing in ruby

Shihua Huang, Alex Szabo

Journal of LuminescenceJul 1, 19966 citations

Temperature and frequency dependent optical dephasing of impurities in crystals

David Hsu, Leslie J. Root, James L. Skinner

We present a nonperturbative theory of the thermal line broadening of optical transitions due to pure dephasing by phonons. The theory extends previous perturbative results of McCumber and Sturge. The theory is applied to experimental results on mixed organic crystals and ruby. We also present a theory of dephasing at T=0 K due to interacting impurities. Our results predict a frequency dependence to 1/T2. We analyze experiments on Y2O3:Eu3+ by Macfarlane and Shelby with this theory, and are able to comment on the nature of inhomogeneous broadening in this system.We present a nonperturbative theory of the thermal line broadening of optical transitions due to pure dephasing by phonons. The theory extends previous perturbative results of McCumber and Sturge. The theory is applied to experimental results on mixed organic crystals and ruby. We also present a theory of dephasing at T=0 K due to interacting impurities. Our results predict a frequency dependence to 1/T2. We analyze experiments on Y2O3:Eu3+ by Macfarlane and Shelby with this theory, and are able to comment on the nature of inhomogeneous broadening in this system.

AIP conference proceedingsJan 1, 19860 citations

Stimulated emission and dynamic feedback of phonons in ruby

Peter A. Fokker, J. I. Dijkhuis, H. W. de Wijn

Journal of LuminescenceJul 1, 19923 citations

According to several recent studies, the width of the sharp zero-phonon lines in the electronic spectra of impurities in solids, such as the

R

lines of ruby, is due to Raman scattering of phonons by the impurity ions. The question whether such zero-phonon lines are homogeneously broadened is an important one, both for its own interest and for optical-maser applications. From a detailed study of the stimulated-emission spectra of a ruby laser operating in the traveling-wave modes, we obtain conclusive evidence that such zero-phonon lines are homogeneously broadened. Because the

{R}_{1}

line of ruby is essentially homogeneously broadened at room temperature, the traveling-wave laser oscillates for all practical purposes only in a single mode. The spectral width of the laser emission is extremely sharp. It is less than 0.005 ${\mathrm{cm}}^{\ensuremath{-}1}$ at room temperature as compared to a width of the order of 1 ${\mathrm{cm}}^{\ensuremath{-}1}$ for conventional ruby lasers of comparable intensity. In addition, the output intensity no longer shows random spikes but shows a predictable train of regularly spaced spikes which agree well with theory.