Stimulated emission of phonons in a ruby fiber

Abstract
Avalanches of resonant phonons generated by stimulated emission within the optically excited Ē(2E) doublet are observed in a 400-μm thick fiber of single-crystalline ruby. In comparison with bulk ruby, the avalanches develop fully in a shorter time because the phonons are confined to the active medium by reflection from the fiber boundaries. Position-independent rate equations adequately describe the dynamics.