Direct Imaging of Energy Dissipation in Surface Acoustic Waves

Abstract Unraveling the spatial distribution and energy dissipation of high-frequency surface acoustic waves (SAWs) is essential for advancing nanoacoustic architectures and probing low-dimensional wave–matter interactions. However, visualizing these dynamics at the subwavelength scale remains challenging due to the optical diffraction limit and severe topographic artifacts, such as surface defects and roughness, in scanning probe measurements. Here, we establish scanning thermal microscopy (SThM) as a robust metrological paradigm to map nanoscale energy dissipation and resolve complex acoustic wavefields through their localized thermal signatures. Leveraging this platform, we demonstrate how microgeometries sculpt the acoustic energy landscape and enable quantitative extraction of wave scattering parameters. Furthermore, by interrogating the h-BN/LiNbO3 van der Waals (vdW) interface, we capture localized temperature signatures of interfacial energy exchange. We observe anomalous nonlinear thermal scaling at the 2D heterointerface, consistent with the intrinsic nonlinear damping of the 2D heterostructure. This work highlights the capability of SThM to probe acoustic energy dissipation, establishing a diagnostic framework for subwavelength acoustic wavefields and heterogeneously integrated devices.