Accumulated photon echo in ruby and alexandrite.

Abstract

The technique of picosecond accumulated photon echo is applied to 700-at. ppm ruby and 2000-at. ppm alexandrite. The decay of the photon-echo intensity versus the probe-pulse delay displays a beat. A detailed analysis on the basis of Bloch equations shows that the beat frequency is associated with the zero-field splitting of the $^{4}$${\mathit{A}}_{2}$ ground state, and that its phase and amplitude are determined by the amount of population communication within this state. Precise values for the spontaneous decay time of 2A\ifmmode\bar\else\textasciimacron\fi{}${(}^{2}$E) and the $^{4}$${\mathit{A}}_{2}$ zero-field splitting are derived.