Nonlinear sound amplification in zinc oxide

摘要

The generation and propagation of acoustoelectric domains in ZnO is studied by Brillouin scattering. Special attention is paid to the nonlinear region of sound amplification; it is shown how such experiments can be compared with existing nonlinear theories for the acoustoelectric effect. In particular, the experiments are compared with the parametric theory of Conwell et al. and a theory based on strong bunching effects of Tien and Wonneberger. It is found that at the beginning of gain saturation, the theory of Tien and Wonneberger gives a better fit to the experimental results. However, at slightly increased domain intensities, the parametric processes become dominating before a complete saturation due to carrier bunching has occurred.