Abstract

Cu₂O is a canonical exciton material. The lowest exciton series (the yellow series) exhibits up to 8 distinct terms obeying a hydrogenic relation. We have investigated absorption spectra of highly excited Cu₂O crystals with femtosecond time-resolution following initial injection of electron-hole pairs directly in the form of n=1 excitons. The successive disappearance of the different other terms of the absorption series, starting with the highest terms, is observed as the initial exciton density is increased. This effect is accompanied by an increase of absorption on the high energy side of each discrete absorption line as shown in the figure.

© 1990 Optical Society of America