Fluorescence of Ruby Laser Rods

Abstract

Fluorescence studies of the R-line emission of ruby laser rods over the temperature range of 77 to 300 K have disclosed several new features. In particular, for most of the ruby rods, the fluorescent decay time, τ, was not strictly exponential. Effects of this kind have been observed in the fluorescent decay of the 4F3/2 level of Nd3+ in YAG (yttrium aluminum garnet) and in Nd-doped glasses. In both cases, the nonexponential decay was interpreted as evidence for inhomogeneous line broadening effects, among which are strains, ion clustering, and other defects that modify the crystal field at the ion site. Our observations of nonexponential fluorescent decay in ruby are indicative of inhomogeneous line broadening effects in lightly doped (0/05%) ruby. In fact, inhomogeneous line broadening was observed in ruby at liquid helium temperatures, in the spectroscopic studies of A. L. Schawlow.