title: Physical mechanisms of coherent acoustic phonons generation by ultrafast laser action.
abstract: In this review we address the microscopic mechanisms that are involved in the photogeneration processes of GHz-THz coherent acoustic phonons (CAP) induced by an ultrafast laser pulse. Understanding and describing the underlying physics is necessary indeed for improving the future sources of coherent acoustic phonons useful for the non-destructive testing optoacoustic techniques. Getting more physical insights on these processes also opens new perspectives for the emerging field of the opto-mechanics where lattice motions (surface and/or interfaces ultrafast displacements, nanostructures resonances) are controlled by light. We will then remind the basics of electron-phonon and photon-phonon couplings by discussing the deformation potential mechanism, the thermoelasticity, the inverse piezoelectric effect and the electrostriction in condensed matter. Metals, semiconductors and oxide materials will be discussed. The contribution of all these mechanisms in the photogeneration process of sound will be illustrated over several examples coming from the rich literature.
authors.affiliation: Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, Université du Maine, 72085 Le Mans, France. Electronic address: pascal.ruello@univ-lemans.fr.
authors.forename: Pascal
authors.initials: P
authors.lastname: Ruello
authors.affiliation: Laboratoire d'Acoustique UMR CNRS 6613, Université du Maine, 72085 Le Mans, France.
authors.forename: Vitalyi E
authors.initials: VE
authors.lastname: Gusev
keywords: Electron–phonon coupling; Laser ultrasonics; Nanoacoustics; Ultrafast acoustics; Ultrafast phenomena