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Proceedings Paper

Tunable Bragg extraction of light in photonic quasi crystals: dispersed liquid crystalline metamaterials
Author(s): Massimo Rippa; Eugenia Bobeico; Cesare P. Umeton; Lucia Petti
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Paper Abstract

By exploiting Metamaterials (MTMs) and Photonic Quasi-Crystals (PQCs), it is possible to realize man-made structures characterized by a selective EM response, which can be also controlled by combining the distinctive properties of reconfigurable soft-matter. By finely controlling lattice parameters of a given photonic structure, it is possible to optimize its extraction characteristics at a precise wavelength, or minimize the extraction of undesired modes. In general, however, once a structure is realized, its extraction properties cannot be varied. To cross this problem, it is possible to combine capabilities offered by both MTMs and PQCs with the reconfigurable properties of smart materials, such as Liquid Crystals (LCs); in this way, a completely new class of “reconfigurable metamaterials” (R-MTM) can be realized. We report here on the realization and characterization of a switchable photonic device, working in the visible range, based on nanostructured photonic quasi-crystals, layered with an azodye-doped nematic LC (NLC). The experimental characterization shows that its filtering effect is remarkable with its extraction spectra which can be controlled by applying an external voltage or by means of a laser light. The vertical extraction of the light, by the coupling of the modes guided by the PQC slab to the free radiation via Bragg scattering, consists of an extremely narrow orange emission band at 621 nm with a full width at half-maximum (FWHM) of 8 nm. In our opinion, these results represent a breakthrough in the realization of innovative MTMs based active photonic devices such as tunable MTMs or reconfigurable lasers and active filters.

Paper Details

Date Published: 5 September 2015
PDF: 8 pages
Proc. SPIE 9565, Liquid Crystals XIX, 956516 (5 September 2015); doi: 10.1117/12.2190362
Show Author Affiliations
Massimo Rippa, Institute for Applied Sciences and Intelligent Systems, CNR (Italy)
Eugenia Bobeico, UTTP ENEA Portici Research Ctr. (Italy)
Cesare P. Umeton, Univ. of Calabria (Italy)
Lucia Petti, Institute for Applied Sciences and Intelligent Systems, CNR (Italy)

Published in SPIE Proceedings Vol. 9565:
Liquid Crystals XIX
Iam Choon Khoo, Editor(s)

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