Abstract
A theoretical model for superradiant damping effect in inhomogeneously broadened media and its application to photon-echo problems are discussed. Only optically thin systems are considered, and all nonradiative relaxation mechanisms are neglected. Numerical calculations are performed for a very wide square inhomogeneous line shape and square applied pulses. It is shown that excitation of the system becomes increasingly difficult as the superradiant lifetime becomes comparable with . The energy reradiated after the end of the exciting pulse is considerable for and for some applied pulse areas. Two-pulse sequences produce multiple echoes as the microscopic polarizations spontaneously rephase. The first-echo amplitude maximum is found to occur for first-applied-pulse areas increasingly above as decreases. For a given first-pulse area, the echo intensities increase initially as decreases (negligible damping) and finally decrease and vanish (important damping). The ratio of the second- to first-echo amplitudes is found to be proportional to for small superradiance levels and to decrease when approaches . An approximate estimate of this ratio is derived for the region of linearity in .
- Received 23 October 1969
DOI:https://doi.org/10.1103/PhysRevA.1.1472
©1970 American Physical Society