2D van der WAALs layeRs for sub-picosecond UltraSonics – WAALRUS

Picosecond laser ultrasonics is a well-recognized technique for non-invasive, high-resolution, structural characterization of materials and tissues at a sub-micron scale. It relies on the use of thin films as two-dimensional (2D) transducers, allowing launching and detection of acoustic coherent waves from ultrashort pump and probe laser pulses. The WAALRUS project aims at defining novel ultrathin opto-acoustic transducers based on 2D van der Waals materials, such as graphene, hexagonal boron nitride and transition metal dichalcogenides. Benefiting from their natural atomically thin layer structure with defect free interfaces, these materials will be used to bring opto-acoustic processes down to the ultimate scale of a single atom or a single interface. A resolution range with sub-nanometer acoustic wavelengths and sub-picosecond frequencies will be reached, overcoming current limitations with metallic and III-V thin films. By combining nanofabrication of advanced van der Waals heterostructures and optical femtosecond pump-probe experiments, the consortium will elaborate and investigate original tunable devices towards the fundamental understanding of the mechanical properties of the non-covalent van der Waals bounds, and the demonstration of the superior figures-of-merit of this novel class of versatile transducers.