Fluorescence and Optical Maser Effects in CaF2:Sm++

Measurements are reported of absorption, emission, and activation spectra in Ca${\mathrm{F}}_2$: ${\mathrm{Sm}}^{++}$, and also of fluorescence lifetime. A revised level scheme is proposed. Observations of optical maser effects were made at liquid hydrogen and liquid helium temperatures over a wide range of pumping intensities. For illumination in the 6400-A band, the threshold intensity of illumination was about 20 w ${\mathrm{cm}}^{-2\mathrm{}}$. Observations are reported of the dependence of the intensity of the maser beam on the pumping intensity. Photographic observations, made both with or without a Fabry-Perot etalon, show that on one particular sample five distinct frequencies were present in the maser signal, and that the number of modes excited was of the order of 1000.