A general theoretical and experimental treatment of transient grating diffraction is presented for interfacial holographic gratings in thin film structures. The theoretical treatment allows for gratings that have nonuniform spatial amplitude throughout the sample. Interface selective transient gratings experiments are performed on oriented thin films (approximately 100 nm) of YBa₂Cu₃O_7-x, with MgO and SrTiO₃ substrates. Four different excitation and probe geometries are utilized such that each geometry results in a unique temporal decay. The grating has a significant amplitude on both sides of the film-substrate interface with a grating wave-vector parallel to the interface. The four experimental geometries comprise an over determined system that can be used to confirm the validity of the model assumptions. Numerical fits to the experimental data, using a straight forward diffusive model, are performed to obtain information on thermal diffusivity and to demonstrate the applicability of the technique to monitor anisotropic thermal relaxation processes in thin film- substrate structures. This analysis yields the anisotropic YBa₂Cu₃O_7-x thermal diffusivity constants and the thermal boundary resistance between the thin film and substrate.

Date Published: 17 June 1993
PDF: 12 pages
Proc. SPIE 1861, Ultrafast Pulse Generation and Spectroscopy, (17 June 1993); doi: 10.1117/12.147063

Published in SPIE Proceedings Vol. 1861:
Ultrafast Pulse Generation and Spectroscopy
Timothy R. Gosnell; Antoinette J. Taylor; Keith A. Nelson; Michael C. Downer, Editor(s)