Epitaxial VO2 Nanostructures: A Route to Large-Scale, Switchable Dielectric Metasurfaces

• Published in: ACS photonics Vol. 5; no. 7; pp. 2561 - 2567
• Main Authors: Ligmajer, Filip, Kejík, Lukáš, Tiwari, Uddhab, Qiu, Meng, Nag, Joyeeta, Konečný, Martin, Šikola, Tomáš, Jin, Wei, Haglund, Richard F, Appavoo, Kannatassen, Lei, Dang Yuan
• Format: Journal Article
• Language: English
• Published: American Chemical Society 18.07.2018
• Subjects: metamaterials; vanadium dioxide; phase transition; plasmonics; metasurfaces; near-infrared modulation
• ISSN: 2330-4022; 2330-4022
• DOI: 10.1021/acsphotonics.7b01384

Metasurfaces offer unparalleled functionalities for controlling the propagation and properties of electromagnetic waves. But to transfer these functions to technological applications, it is critical to render them tunable and to enable fast control by external stimuli. In most cases, this has been realized by utilizing tunable materials combined with a top-down nanostructuring process, which is often complicated and time intensive. Here we present a novel strategy for fabricating a tunable metasurface comprising epitaxially grown nanobeams of a phase transition material, vanadium dioxide. Without the need for extensive nanolithographic fabrication, we prepared a large-area (>1 cm2), deep-subwavelength (thickness of ∼λ/40) nanostructured thin film that can control light transmission with large modulation depth, exceeding 9 dB across all telecommunication wavelength bands. Furthermore, the transmission in the “on” state remains higher than 80% from near- to mid-infrared region. This renders our metasurface useful also as a phase-shifting element, which we demonstrate by carrying out cross-polarized transmission measurements. To provide insights about the relationship between metasurface morphology and its resulting optical properties, we perform full-field three-dimensional numerical simulations as a function of width, height, and edge-to-edge separation of the epitaxial VO2 nanobeams.