Interferometric detection of ultrafast thermoelastic transients in thin films: theory with supporting experiment

The thermoelastic generation and interferometric detection of ultrafast the rmal and acoustic transients in a 300-nm-thick tungsten film are theoretica lly predicted and supported through experiment. Detection of these picoseco nd transients is obtained with a time-resolved spectroscopy scheme that use s a rotated cube, common path, self-stabilized Michelson interferometer and subpicosecond laser pulses from a mode-locked laser. These observations ar e theoretically described by the superposition of changes in the complex in dex of refraction and displacements over the absorption volume. Data analys is is completed in both time and frequency domains to support the validity of the classical assumptions involved in the theoretical derivation. (C) 19 99 Optical Society of America [S0740-3224(99)01306-5] OCIS codes: 120.3180, 300.6500, 310.3840, 310.6860, 310.6870, 320.5390.