Unidirectionally excited phonon polaritons in high-symmetry orthorhombic crystals

Authors

• Qing Zhang, School of Physics, University of Electronic Science and Technology of China
• Qingdong Ou, ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
• Guangyuan Si, Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility, Clayton, Victoria, Australia
• Guangwei Hu, CUNY Advanced Science Research CenterFollow
• Shaohua Dong, Department of Electrical and Computer Engineering, National University of Singapore
• Yang Chen, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China
• Jincheng Ni, Department of Electrical and Computer Engineering, National University of Singapore
• Chen Zhao, Department of Electrical and Computer Engineering, National University of Singapore
• Michael S. Fuhrer, ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia
• Yuanjie Yang, School of Physics, University of Electronic Science and Technology of China
• Andrea Alù, CUNY Advanced Science Research CenterFollow
• Rainer Hillenbrand, CIC nanoGUNE BRTA and Department of Electricity and Electronics, UPV/EHU, Donostia-San Sebastián, Spain
• Cheng-Wei Qiu, Department of Electrical and Computer Engineering, National University of Singapore

Document Type

Article

Publication Date

7-29-2022

Abstract

Advanced control over the excitation of ultraconfined polaritons—hybrid light and matter waves—empowers unique opportunities for many nanophotonic functionalities, e.g., on-chip circuits, quantum information processing, and controlling thermal radiation. Recent work has shown that highly asymmetric polaritons are directly governed by asymmetries in crystal structures. Here, we experimentally demonstrate extremely asymmetric and unidirectional phonon polariton (PhP) excitation via directly patterning high-symmetry orthorhombic van der Waals (vdW) crystal α-MoO3. This phenomenon results from symmetry breaking of momentum matching in polaritonic diffraction in vdW materials. We show that the propagation of PhPs can be versatile and robustly tailored via structural engineering, while PhPs in low-symmetry (e.g., monoclinic and triclinic) crystals are largely restricted by their naturally occurring permittivities. Our work synergizes grating diffraction phenomena with the extreme anisotropy of high-symmetry vdW materials, enabling unexpected control of infrared polaritons along different pathways and opening opportunities for applications ranging from on-chip photonics to directional heat dissipation.

Comments

This article was originally published in Science Advances, available at http://dx.doi.org/10.1126/sciadv.abn9774

This work is distributed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).