ABSTRACT
For nearly two decades, starting from the prediction of super-radiance by R. H. Dicke in 1954, the subject was generally considered as being mainly of theoretical significance. The situation changed in 1973 when Skribanowitz, Herman, MacGillivray and Feld performed experiments with low-pressure HF gas, and realized conditions where the phase memory time of the radiation centres was longer than the cooperative spontaneous emission time. This chapter describes the numerous super-radiance experiments. It demonstrates that conditions for the experimental realization of super-radiance do exist, that is under appropriate circumstances super-radiance is not suppressed by de-phasing or inhomogeneous relaxation. The experiments can be divided into two classes with respect to the time scale of the relaxation processes. In gases, the relaxation times are typically in the nanosecond range, whereas in solids these processes are faster, by at least one or two orders of magnitude. The chapter gives a description of some of these experiments both in gases and in solids.
