Abstract

van der Waals (vdW) materials supporting phonon polaritons (PhPs) – light coupled to lattice vibrations – have gathered significant interest because of their intrinsic anisotropy and low losses. In particular, α-MoO3 supports PhPs with in-plane anisotropic propagation, which has been exploited to tune the optical response of twisted bilayers and trilayers. Additionally, various studies have explored the realization of polaritonic crystals (PCs) – lattices with periods comparable to the polariton wavelength. PCs consisting of hole arrays etched in α-MoO3 slabs exhibit Bragg resonances dependent on the angle between the crystallographic axes and the lattice vectors. However, such PC concept, with a fixed orientation and size of its geometrical parameters, constrains practical applications and introduces additional scattering losses due to invasive fabrication processes. Here, we demonstrate a novel PC concept that overcomes these limitations, enabling low-loss optical tuning. It comprises a rotatable pristine α-MoO3 layer located on a periodic hole array fabricated in a metallic layer. Our design prevents degradation of the α-MoO3 optical properties caused by fabrication, preserving its intrinsic low-loss and in-plane anisotropic propagation of PhPs. The resulting PC exhibits rotation of the Bloch modes, which is experimentally visualized by scanning near-field microscopy. In addition, we experimentally determine the polaritons momentum and reconstruct their band structure. These results pave the way for mechanically tunable nano-optical components based on polaritons for potential lasing, sensing, or energy harvesting applications.

Details

Title
Twist-tunable in-plane anisotropic polaritonic crystals
Author
Capote-Robayna, Nathaniel 1 ; Tresguerres-Mata, Ana I F 2 ; Aitana Tarazaga Martín-Luengo 2 ; Terán-García, Enrique 2 ; Martin-Moreno, Luis 3 ; Alonso-González, Pablo 2 ; Nikitin, Alexey Y 4 

 Applied Physics Department, Engineering School of Gipuzkoa, University of the Basque Country (UPV/EHU), Donostia-San Sebastián, 20018, Spain; 226245Donostia International Physics Center (DIPC), Donostia-San Sebastián, 20018, Spain 
 Department of Physics, University of Oviedo, Oviedo, 30006, Spain; Center of Research on Nanomaterials and Nanotechnology, CINN (CSIC-Universidad de Oviedo), El Entrego, 33940, Spain 
 Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain; Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, 50009, Spain 
 226245Donostia International Physics Center (DIPC), Donostia-San Sebastián, 20018, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain 
Pages
4761-4770
Publication year
2024
Publication date
2024
Publisher
Walter de Gruyter GmbH
ISSN
21928606
e-ISSN
21928614
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3138965953
Copyright
© 2024. This work is published under http://creativecommons.org/licenses/by/4.0 (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.