Abstract

Experiments investigating the process of Bose-Einstein condensation of excitons in Cu2O will be reviewed. The exciton flux reaching the back surface of mm thick single crystals is investigated following creation of a high density of excitons close to the front surface with a pulsed laser. An anomalous propagation regime is observed at. sufficiently low crystal temperatures and sufficiently high particle densities, in the form of a ballistic packet progressing at a velocity close to the crystal sound velocity. The ballistic packet is attributed to an excitonic superfluid, the result of a Bose-Einstein Condensation (BEC). Conditions for appearance of the ballistic excitonic transport are found to be in good agreement with the predictions of the weakly interacting Bose gas model.

© 1997 Optical Society of America