Laser-Induced Fluorescence-Line Narrowing in Ruby

Abstract

Using resonance ruby-laser excitation, narrowing of the ruby ${R}_{1}$ fluorescence line to width 0.002 ${\mathrm{cm}}^{\ensuremath{-}1}$ at 4.2\ifmmode^\circ\else\textdegree\fi{}K is observed. Absence of spectral diffusion indicates that a short-range interaction rather than earlier postulated multipolar interactions is responsible for energy transfer in concentrated ruby.