Phénomènes Ultra-Rapides et dynamique photoinduite


Objectives : The methods of sound generation (opto-acoustics) and detection (acousto-optics) by lasers are finding numerous applications for the noncontact and non-destructive testing of materials and evaluation of physical processes. In the lectures various physical mechanisms for the transformation of optical energy in acoustical energy in different types of materials (metals, semiconductors and dielectrics) are analyzed. The generation and detection of both bulk and surface acoustic waves are studied. Particular emphasis is given to an analysis of opportunities to generate by ultrafast lasers of hypersound for the diagnostics of the thin films, multilayered coatings and nanostructured materials. The principles of the detection of hypersound by lasers are also discussed

Programme :
• Introduction. Application of laser-generated acoustic waves in non-destructive testing and fundamental research.
• Physical mechanisms of opto-acoustic transformation in dielectrics; metals and semiconductors. From laser-generated thermal and diffusional waves towards laser-generated strain waves.
• Laser generation of GHz-THz frequency acoustic waves for testing of nanomaterials and nanostructures. Physical principles for generation of picosecond acoustic pulses.
• Physical principles of the acousto-optic transformation.
• Detection of ultrashort acoustic pulses through the acousto-optic effect.
• Generation and detection by lasers of the surface acoustic waves. Application of laser generated surface, interface and bulk skimming acoustic waves for the evaluation of the elastic properties of materials at high pressures and high temperatures, and for the detection of cracks

En bref

Crédits ECTS 2