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Proceedings Paper

Nonresonant ENZ metamaterial at visible wavelength for superior refractive index matching sensing
Author(s): Z. Fusco; M. Taheri; M. Rahmani; D. Neshev; T. White; A. Tricoli
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Paper Abstract

In the compelling race of finding alternative plasmonic material, metallic sodium tungsten bronzes, NaxWO3 with x<0.25, host promising optoelectronic properties emerging from the insulator-metal transition (IMT), such as strong interband transition and intense near-infrared plasmonic absorption. So far, studies have focused on tuning the IR plasmonic properties for the realization of functional devices, ranging from biosensors to smart windows. However, the utilization of the transparency band where the permittivity approaches zero still remains largely unexplored. Here, we show preliminary results which indicates an epsilon-near-zero (ENZ) behavior at optical frequencies of NaxWO3 which arises from the minimization of the total scattering cross-section. Additionally, as a proof of concept, we explore this material for sensing applications and we establish a performant optical sensor with sensitivity of 150 nm/RIU and showing a threefold enhancement with respect to traditional Au nanospheres. The peculiar sensing mechanism is investigated both experimentally and theoretically by means of electrodynamic and first principle calculations. Combined with the high quality of the NaxWO3 single crystals, ENZ properties in the ~400-600 nm region and low losses, these new insights offer great promise for the inexpensive realization of new generations of electro-optical devices with application ranging from ultrasensitive biosensors and light harvesting to exotic cloaking materials.

Paper Details

Date Published: 31 December 2019
PDF: 3 pages
Proc. SPIE 11201, SPIE Micro + Nano Materials, Devices, and Applications 2019, 112010H (31 December 2019); doi: 10.1117/12.2539851
Show Author Affiliations
Z. Fusco, The Australian National Univ. (Australia)
M. Taheri, The Australian National Univ. (Australia)
M. Rahmani, The Australian National Univ. (Australia)
D. Neshev, The Australian National Univ. (Australia)
T. White, The Australian National Univ. (Australia)
A. Tricoli, The Australian National Univ. (Australia)

Published in SPIE Proceedings Vol. 11201:
SPIE Micro + Nano Materials, Devices, and Applications 2019
M. Cather Simpson; Saulius Juodkazis, Editor(s)

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