TRANSIENT GRATING DIFFRACTION FROM AN INTERFACE BETWEEN 2 MATERIALS - THEORY AND EXPERIMENTAL APPLICATION

A general theory for transient grating diffraction from both sides of a single interface is developed. The grating is assumed to have an arbitrary amplitude on both sides of a bound interface with the grating wave vector parallel to the interface. The specific spatial origin of the diffracted light is described for both the reflected and the transmitted geometries of diffraction. In the reflected geometry the signal is dominated by diffraction from a region near the interface that is a small fraction of an optical wavelength wide. The transmitted geometry signal measures primarily the mean bulk properties of the sample. An experimental example of thermal-transient grating diffraction from a YBa2Cu3O7-x/SrTiO3 interface is presented. Model calculations for the experimental data are performed to demonstrate that the approach can be used to monitor spatially nonuniform transient grating temporal relaxation.