Unlocking Optical Coupling Tunability in Epsilon-Near-Zero Metamaterials Through Liquid Crystal Nanocavities

Year: 2024

Authors: Lio GE., Ferraro A., Zappone B., Parka J., Schab-Balcerzak E., Umeton CP., Riboli F., Kowerdziej R., Caputo R.

Autors Affiliation: Univ Florence, Phys Dept, I-50019 Florence, Italy; European Lab non Linear Spect LENS, I-50019 Florence, Italy; Consiglio Nazl Ric Ist Nanotecnol CNR Nanotec, I-87036 Arcavacata Di Rende, CS, Italy; Mil Univ Technol, Inst Appl Phys, 2 Kaliskiego Str, PL-00908 Warsaw, Poland; Polish Acad Sci, Ctr Polymer & Carbon Mat, 34 M Curie Sklodowska Str, PL-41819 Zabrze, Poland; Univ Calabria, Phys Dept, I-87036 Arcavacata Di Rende, CS, Italy; CNR INO, Natl Inst Opt, I-50019 Sesto Fiorentino, FI, Italy; Univ Elect Sci & Technol China, Inst Fundamental & Frontier Sci, Chengdu 610054, Peoples R China.

Abstract: Epsilon-near-zero (ENZ) metamaterials represent a powerful toolkit for selectively transmitting and localizing light through cavity resonances, enabling the study of mesoscopic phenomena and facilitating the design of photonic devices. In this experimental study, it demonstrates the feasibility of engineering and actively controlling cavity modes, as well as tuning their mutual coupling, in an ENZ multilayer structure. Specifically, by employing a high-birefringence liquid crystal film as a tunable nanocavity, the polarization-dependent coupling of resonant modes with narrow spectral width and spatial extent is achieved. Surface forces apparatus (SFA) allowed to continuously and precisely control the thickness of the liquid crystal (LC) film contained between the nanocavities and thus vary the detuning between the cavity modes. Hence, it is able to manipulate nanocavities anti-crossing behaviors. The suggested methodology unlocks the full potential of tunable optical coupling in epsilon-near-zero metamaterials and provides a versatile approach to the creation of tunable photonic devices, including bio-photonic sensors and/or tunable planar metamaterials for on-chip spectrometers. A high birefringence liquid crystal (Delta n approximate to 0.4) is squeezed between two epsilon near zero metamaterials forming a nanocavity whose thickness is dynamically varied through surface force apparatus. This allows confining the electric field and correlated modes at different wavelengths. Furthermore, the anti-cross behavior is highlighted by varying the cavity thickness or switching the LC refractive index changing the input light polarization.image

Journal/Review: ADVANCED OPTICAL MATERIALS

Volume: 12 (13)      Pages from:   to:

More Information: This research was performed in the framework of the bilateral (Italy-Poland) project: Active metamaterials based on new generation liquid crystals (LCMETA) funded by the Italian Ministry of Foreign Affairs and International Cooperation and the Polish National Agency for Academic Exchange NAWA. G.E.L and F.R. thank the FASPEC (Fiber-Based Planar Antennas for Biosensing and Diagnostics) – supported by Tuscany region in the Horizon 2020 framework – and the project Complex Photonic Systems (DFM.AD005. 317). G.E.L. also thanks the research project FSE-REACT EU financed by National Social Fund – National Operative Research Program and Innovation 2014-2020 (DM 1062/2021). A.F and R.C thank the project DEMETRA – Sviluppo di tecnologie di materiali e di tracciabilita per la sicurezza e la qualita dei cibi PON ARS01 00401. R.K. and J.P. acknowledged the financial support from the MUT University Grant UGB 22 804 from funds for year 2023.
KeyWords: ENZ; high-birefringence liquid crystal; liquid crystals; metamaterials; nano optical-cavities
DOI: 10.1002/adom.202302483

Citations: 3
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