J. Phys. IV France
Volume 125, June 2005
Page(s) 361 - 363

J. Phys. IV France 125 (2005) 361-363

DOI: 10.1051/jp4:2005125084

Direct measurement of ultrafast surface displacement in laser picosecond acoustics

O. Matsuda, K. Aoki, T. Tachizaki and O.B. Wright

Department of Applied Physics, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan

Picosecond acoustic pulses generated in solids with ultrashort optical pulses can be detected through the reflectance or phase changes of optical probe pulses. The detection relies on acousto-optic coupling resulting from a combination of the photoelastic effect and transient surface displacements. The acoustic strain pulse shape gives access to the ultrafast dynamics of the electrons that influence the generation process. This pulse shape is directly related to the contribution to the probe light modulation resulting from surface displacement. Here we present a method that allows the discrimination between the photoelastic and surface displacement contributions using a novel oblique optical incidence geometry, allowing the strain pulse shape to be directly obtained in a single measurement.

© EDP Sciences 2005