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arXiv · 2004.14599

Twisted Nano-optics: Manipulating Light at the Nanoscale with Twisted Phonon Polaritonic Slabs

Jiahua Duan·Nathaniel Capote-Robayna·Javier Taboada-Gutierrez·Gonzalo Alvarez-Perez·Ivan Prieto·Javier Martin-Sanchez·Alexey Y. Nikitin·Pablo Alonso-Gonzalez
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Abstract

Recent discoveries have shown that when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between their respective in-plane principal axes, 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 polaritons, hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a polar vdW crystal (MoO3) supporting low-loss anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources (metal antennas). Our images reveal that under a critical angle the PhPs isofrequency curve (determining the PhPs momentum at a fixed frequency) undergoes a topological transition. Remarkably, at this angle, the propagation of PhPs is strongly guided along predetermined directions (canalization regime) with no geometrical spreading (diffraction-less). These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nano-imaging, (bio)-sensing, quantum applications and heat management.

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Jiahua Duan, Nathaniel Capote-Robayna, Javier Taboada-Gutierrez, Gonzalo Alvarez-Perez, Ivan Prieto, Javier Martin-Sanchez, Alexey Y. Nikitin, Pablo Alonso-Gonzalez. 2020-04-30. Twisted Nano-optics: Manipulating Light at the Nanoscale with Twisted Phonon Polaritonic Slabs. https://doi.org/10.1021/acs.nanolett.0c01673

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