Nanoscale Guiding of Infrared Light with Hyperbolic Volume and Surface Polaritons in van der Waals Material Ribbons

Autor: Peining Li, Pablo Alonso-González, Irene Dolado, Alexey Y. Nikitin, Saül Vélez, Luis E. Hueso, James H. Edgar, Song Liu, Elizaveta Nikulina, Fèlix Casanova, Rainer Hillenbrand, Francisco Javier Alfaro-Mozaz, Andrei Bylinkin
Rok vydání: 2020
Předmět:
Zdroj: Advanced Materials
ISSN: 0935-9648
DOI: 10.1002/adma.201906530
Popis: Van der Waals (vdW) materials host a variety of polaritons, which make them an emerging material platform for manipulating light at the nanoscale. Due to the layered structure of vdW materials, the polaritons can exhibit a hyperbolic dispersion and propagate as nanoscale-confined volume modes in thin flakes. On the other hand, surface-confined modes can be found at the flake edges. Surprisingly, the guiding of these modes in ribbons-representing typical linear waveguide structures-is widely unexplored. Here, a detailed study of hyperbolic phonon polaritons propagating in hexagonal boron nitride ribbons is reported. Employing infrared nanoimaging, a variety of modes are observed. Particularly, the fundamental volume waveguide mode that exhibits a cutoff width is identified, which, interestingly, can be lowered by reducing the waveguide thickness. Further, hybridization of the surface modes and their evolution with varying frequency and waveguide width are observed. Most importantly, it is demonstrated that the symmetrically hybridized surface mode does not exhibit a cutoff width, and thus enables linear waveguiding of the polaritons in arbitrarily narrow ribbons. The experimental data, supported by simulations, establish a solid basis for the understanding of hyperbolic polaritons in linear waveguides, which is of critical importance for their application in future photonic devices.
Databáze: OpenAIRE
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