Nonlinear resonant attenuation in glasses and spectral diffusion

Abstract
We have developed a quantitative theory of two nonlinear low-temperature phenomena in dielectric glasses for which interaction of two-level systems (TLS’s) is responsible. They are the nonlinear resonant ultrasonic or microwave absorption and hole burning. General formulas are obtained for the critical intensity determining the onset of nonlinear behavior of resonant absorption and for the form of the burned hole with regard to the spectral diffusion. These formulas are investigated in detail for various limiting cases.