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Obst M, Nörenberg T, Álvarez-Pérez G, de Oliveira TVAG, Taboada-Gutiérrez J, Feres FH, Kaps FG, Hatem O, Luferau A, Nikitin AY, Klopf JM, Alonso-González P, Kehr SC, Eng LM. Terahertz Twistoptics-Engineering Canalized Phonon Polaritons. ACS Nano 2023; 17:19313-19322. [PMID: 37738305 DOI: 10.1021/acsnano.3c06477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
The terahertz (THz) frequency range is key to studying collective excitations in many crystals and organic molecules. However, due to the large wavelength of THz radiation, the local probing of these excitations in smaller crystalline structures or few-molecule arrangements requires sophisticated methods to confine THz light down to the nanometer length scale, as well as to manipulate such a confined radiation. For this purpose, in recent years, taking advantage of hyperbolic phonon polaritons (HPhPs) in highly anisotropic van der Waals (vdW) materials has emerged as a promising approach, offering a multitude of manipulation options, such as control over the wavefront shape and propagation direction. Here, we demonstrate the THz application of twist-angle-induced HPhP manipulation, designing the propagation of confined THz radiation between 8.39 and 8.98 THz in the vdW material α-molybdenum trioxide (α-MoO3), hence extending twistoptics to this intriguing frequency range. Our images, recorded by near-field optical microscopy, show the frequency- and twist-angle-dependent changes between hyperbolic and elliptic polariton propagation, revealing a polaritonic transition at THz frequencies. As a result, we are able to allocate canalization (highly collimated propagation) of confined THz radiation by carefully adjusting these two parameters, i.e. frequency and twist angle. Specifically, we report polariton canalization in α-MoO3 at 8.67 THz for a twist angle of 50°. Our results demonstrate the precise control and manipulation of confined collective excitations at THz frequencies, particularly offering possibilities for nanophotonic applications.
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Affiliation(s)
- Maximilian Obst
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Tobias Nörenberg
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Gonzalo Álvarez-Pérez
- Department of Physics, University of Oviedo, Oviedo 33006, Spain
- Center of Research on Nanomaterials and Nanotechnology CINN (CSIC-Universidad de Oviedo), El Entrego 33940, Spain
| | - Thales V A G de Oliveira
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Javier Taboada-Gutiérrez
- Department of Quantum Matter Physics, Université de Genève, 24 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Flávio H Feres
- Gleb Wataghin Physics Institute, University of Campinas (Unicamp), Campinas, Sao Paulo 13083-859, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-100, Brazil
| | - Felix G Kaps
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Osama Hatem
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
- Department of Engineering Physics and Mathematics, Faculty of Engineering, Tanta University, Tanta 31511, Egypt
| | - Andrei Luferau
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Alexey Y Nikitin
- Donostia International Physics Center (DIPC), Donostia/San Sebastián 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Spain
| | - J Michael Klopf
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany
| | - Pablo Alonso-González
- Department of Physics, University of Oviedo, Oviedo 33006, Spain
- Center of Research on Nanomaterials and Nanotechnology CINN (CSIC-Universidad de Oviedo), El Entrego 33940, Spain
| | - Susanne C Kehr
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
| | - Lukas M Eng
- Institut für Angewandte Physik, Technische Universität Dresden, Dresden 01187, Germany
- Würzburg-Dresden Cluster of Excellence - EXC 2147 (ct.qmat), Dresden 01062, Germany
- Collaborative Research Center 1415, Technische Universität Dresden, Dresden 01069, Germany
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