Transition from superfluorescence to amplified spontaneous emission

The cooperative emission process in KCL;${\mathrm{O}}_2$${\mathrm{}}^{\mathrm{-}}$ has been studied as a function of the dephasing rate of the transition dipole. As the temperature of the sample is increased from 10 to 30 K, the emission evolves continuously from that characteristic of superfluorescence to that of amplified spontaneous emission. These results are in qualitative agreement with the predictions of current theories, but quantitative agreement is obtained only when current theories are modified so that the noise source that initiates the emission process is allowed to act continuously during the superfluorescent buildup.