Abstract
An experimental and theoretical study of nonlinear acoustic propagation in a typical glass, fused silica, is presented, at frequencies near 1 GHz and temperatures below 1 K. The data are interpreted within a general framework of pulse propagation in an inhomogeneously broadened two-level absorber. Numerical solutions are compared with the temperature and pulse-width dependence of the critical saturation intensity, as well as with saturation recovery experiments. The data are described by a linewidth of the intrinsic tunneling states that agrees with lifetimes obtained from phonon echo experiments. The distribution of relaxation times which emerges from the analysis of saturation recovery experiments is also understandable within the tunneling model. An improved estimate for the longitudinal deformation potential is eV. For K, the behavior of the pulse velocity is indicative of a coherent propagating mode, i.e., self-induced transparency.
- Received 21 October 1982
DOI:https://doi.org/10.1103/PhysRevB.27.3697
©1983 American Physical Society