Abstract

We have studied the nature of the emission from a laser-excited $\text{KCI}:{\text{O}}_2^{-}$ crystal and have observed that the emission evolves continuously from superfluorescence (SF) to amplified spontaneous emission (ASE) as the temperature of the crystal and hence the dephasing rate of the optical transition are increased. The sample is excited by a 30-ps pulse from a frequency-quadrupled Nd:YAG laser, and the 629.1-nm emission is detected using a streak camera system. At a temperature of 10 K the emission is characterized as SF with an average delay time of 200 ps and an average pulse width of 60 ps. As the temperature is increased to ~20 K, the output pulse broadens and the time delay increases to its maximum value of ~2 ns. As the temperature is increased still further, the time delay is observed to decrease, and at a temperature of 30 K the emission is characterized as ASE with a very small delay time and with an exponentially decaying time evolution. We modeled our experiment using the Maxwell-Bloch formalism and find good agreement for our measured output pulse shapes and for the dependence of delay time and pulse width on the dephasing rate.

© 1986 Optical Society of America