title: Fundamentals of picosecond laser ultrasonics.
abstract: The aim of this article is to provide an introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses. This method can be used to characterize materials with nanometer spatial resolution. With reference to key experiments, we first review the theoretical background for normal-incidence optical detection of longitudinal acoustic waves in opaque single-layer isotropic thin films. The theory is extended to handle isotropic multilayer samples, and is again compared to experiment. We then review applications to anisotropic samples, including oblique-incidence optical probing, and treat the generation and detection of shear waves. Solids including metals and semiconductors are mainly discussed, although liquids are briefly mentioned.
authors.affiliation: Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan. Electronic address: omatsuda@eng.hokudai.ac.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsuda
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 14, 00161 Roma, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Larciprete
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 14, 00161 Roma, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Li Voti
authors.affiliation: Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
authors.forename: Oliver B
authors.initials: OB
authors.lastname: Wright
keywords: Gigahertz and terahertz acoustic waves; Green’s function; Interferometer; Longitudinal and shear acoustic waves; Optical pump-probe technique