Abstract

Optical pumping has been performed on vertical structures, concentrating on the very first picoseconds after the excitation. Above threshold, laser emission is observed, which can take place at two or more different wavelengths, corresponding to longitudinal modes of the Fabry-Perot cavity. Lasing occurs sequentially, the high-energy line appearing before the low-energy one. This shows that transient gain may be large enough to induce lasing over a wide spectral range, up to 46 nm in the present case.

© 1992 The Author(s)