TY - JOUR AB - Recent discoveries have shown that, when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between them, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating phonon polaritons–hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a vdW crystal (α-MoO3) supporting anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources. Our images reveal that, under a critical angle, the PhPs isofrequency curve undergoes a topological transition, in which the propagation of PhPs is strongly guided (canalization regime) along predetermined directions without geometric spreading. These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nanoimaging, (bio)-sensing, or heat management. AU - Duan, Jiahua AU - Capote-Robayna, Nathaniel AU - Taboada-Gutiérrez, Javier AU - Álvarez-Pérez, Gonzalo AU - Prieto Gonzalez, Ivan AU - Martín-Sánchez, Javier AU - Nikitin, Alexey Y. AU - Alonso-González, Pablo ID - 10866 IS - 7 JF - Nano Letters KW - Mechanical Engineering KW - Condensed Matter Physics KW - General Materials Science KW - General Chemistry KW - Bioengineering SN - 1530-6984 TI - Twisted nano-optics: Manipulating light at the nanoscale with twisted phonon polaritonic slabs VL - 20 ER -