Controlling how light propagates and is confined on nanometre scales is a central challenge in both fundamental photonics research and the development of nanoscale optical technologies. Strong progress in this area has come from using crystal anisotropy to guide electromagnetic energy far below the diffraction limit, especially in engineered stacks of twisted van der Waals materials. However, the opportunities anisotropic bulk crystals could offer remain much less explored. In this presentation, we demonstrate that ferroelastic twin walls in the distorted perovskite LaAlO3 act as an intrinsic and natural platform for broadband nanoscale light confinement and highly efficient canalisation. These atomically well-defined interfaces, which separate domains with different crystallographic orientations, localise electromagnetic fields without the need for any nanofabrication. The resulting optical modes can be confined laterally to dimensions up to 260 times smaller than the corresponding free-space wavelength. We further show that, depending on frequency and domain arrangement, twin-wall networks can either attract or expel electromagnetic energy, highlighting their potential as natural elements for broadband mid-infrared and terahertz polaritonic circuitry.
Location: Stuckelberg, Ecole de Physique
Time: Thursday 23 April 2026, 12:30 for pizza, 13:00 start discussion
