Demonstration of highly efficient photon echoes

Highly efficient two-pulse and stimulated photon echoes are experimentally demonstrated in an absorbing medium. Recall efficiencies of 235% and 150% w ith excellent signal contrast are measured for two-pulse and stimulated pho ton echoes, respectively, in a Tm:YAG crystal with an absorption length of 3.8. The reported efficiencies do not include any correction for decay or b eam profile. We believe that this is the first demonstration of an uncorrec ted echo efficiency greater than 100% with good signal fidelity in an optic ally thick medium. (C) 2000 Optical Society of America OCIS codes: 210.4680 , 210.2860, 200.4740.