Simulation of multiwavelength conditions in laser picosecond ultrasonics

Complete numerical simulations are given under SciLab® and MATLAB® coding environments, concerning propagative acoustic wavefronts, for laser picosecond ultrasonics under multiwavelength conditions. Simulations of the deformation field and its propagation into bulk material are given under different wavelength configurations for optical pump and probe beams, which are used to generate and to detect the acoustic signal. Complete insights concerning the dynamics of the acoustic waves are given, considering the absence of carrier diffusions into the material. Several numerical approaches are proposed concerning both the functions introduced to simulate the wavefront ( Heaviside or error) and the coding approach (linear/vectorized/ Oriented Object Programming), under the pure thermo-elastic approach.

Looking Inside Micro- and Nano-Mechanical Pillar Resonators: A Picosecond Ultrasonics Approach

Pillar-shaped Gallium arsenide (GaAs) micromechanical resonators are fabricated, and the feasibility to measure the inside of the pillars in the axial direction with laser-induced GHz ultrasound based on picosecond ultrasonics is tested. Measurements on the pillars with head sizes in the µm range show excellent agreement with theoretical predictions.