04 febbraio 2019

Ferroelectric perovskites for giant refraction

Seminario di Dottorato in Scienza e Nanotecnologia dei Materiali

Lunedì 4 febbraio 2019
Ore 14.30
Sala Seminari, Piano I, Edificio U5 – via Roberto Cozzi 55, Milano

Relatore: Timothy C. H. Liew – School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore

Titolo: Ferroelectric perovskites for giant refraction

Abstract. In principle, materials with a broadband giant index of refraction overcome chromatic aberration and shrink the diffraction limit down to the nanoscale, allowing new opportunities for nanoscopic imaging. They also open alternative avenues for the management of light to improve the performance of photovoltaic cells. Recent advances have demonstrated the feasibility of a giant refractive index in metamaterials at microwave and terahertz frequencies, but the highest reported broadband index of refraction in the visible is n<5. We report a ferroelectric perovskite with an index of refraction of n>26 across the entire visible spectrum and demonstrate its behaviour
using white-light and laser refraction and diffraction experiments. The sample, a solid-solution KTN:Li perovskite, has a naturally occurring room-temperature phase that propagates visible light along its normal axis without significant diffraction or chromatic dispersion, irrespective of beam size, intensity and angle of incidence.