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POLICRYPS composite structures: realization, characterization and exploitation for electro-optical and all-optical applications

2013; Taylor & Francis; Volume: 1; Issue: 1 Linguagem: Inglês

10.1080/21680396.2012.742743

2168-0418

Luciano De Sio, Alessandro Veltri, Roberto Caputo, Antonio De Luca, Giuseppe Strangi, Roberto Bartolino, Cesare Umeton,

Photorefractive and Nonlinear Optics

Abstract The acronym POLICRYPS indicates a nano/micro composite structure made of films of well aligned nematic liquid crystal (NLC) alternated to slices of almost pure polymer. Structures are fabricated by curing a homogeneous mixture of mesogenic material, monomer and a curing agent with UV radiation, under suitable physical and geometrical conditions. In particular, geometrical conditions determine (in the range 0.2 ÷ 15 μ m) the spatial periodicity of the realized sample, which can be utilized for transmitting, diffracting or reflecting an impinging light beam, with negligible scattering losses. The spatial modulation of the refractive index (from polymer to NLC) can be switched ON and OFF both by applying an electric field of few V/μ m or, in some cases, by irradiating the sample with a light beam of suitable wavelength. This electrical/optical tuneability is responsible for a series of distinctive characteristics of the optical effects produced by the structure, and determines the range of possible applications. In fact, in different geometries, the POLICRYPS can be exploited as a switchable holographic grating, a switchable optical phase modulator, a switchable beam splitter, a tuneable Bragg filter or it can be exploited as an electro-optical edge filter in an optical interrogation system. Keywords: liquid crystalscomposite structuresholographic structuresdiffraction gratingsoptical devices Acknowledgements We are pleased to acknowledge the cooperation of all the co-authors of the articles: Sameh Ferjani, Luigia Pezzi, Alessandro Tedesco, Ivan Trebisacce from our Department; Giovanni Gilardi, Rita Asquini, Antonio d'Alessandro, from Dipartimento di Ingegneria dell'Informazione, Elettronica e Telecomunicazioni, Sapienza Università di Roma; Domenico Donisi, Romeo Beccherelli, from Istituto per la Microelettronica e Microsistemi (CNR-IMM), Roma; Michele A. Caponero from ENEA Centro Ricerche Frascati, Roma; Svetlana Serak, Nelson Tabiryan, from Beam Engineering for Advanced Measurements Company, Orlando (USA); Andrei Sukhov, from the Institute for Problems in Mechanics, Russian Academy of Science, Moscow (Russia).