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March 18

“Pattern formation for stimuli directed chiral nematic diffraction gratings”

Rafael Zola  UTFPR, Brazil

Starts at 9h00 am

The ability to control light direction with tailored precision via facile means is long-desired in science and industry. A periodic structure called diffraction grating is a key component for the task, nowadays present in wavelength division multiplexing devices, monochromators, lasers, spectrometers, media storage, beam steering, and many other applications. Next-generation optical devices, however, demand nonmechanical, full and remote control, besides generating higher than 1D diffraction patterns with as few optical elements as possible. Chiral nematic liquid crystals are great candidates to act as controllable diffraction gratings, since they present a natural modulation that can be tuned by several different stimuli. In this talk, we present some recent developments on generating gratings and patterns that can be used as gratings by using chiral nematic liquid crystals. We start by discussing the thermally controlled grating that forms upon a wetting transition, as well as a few characteristics on the formation process. Next, we present a photo and electrically controllable grating that can be used to form zigzag patterns and consequently act as diffraction gratings. Last, we discuss simulation results that provide some ways of fabricating modulated structures with chiral nematics by means of patterned substrates, where the interplay of chirality, elasticity and boundary conditions lead to several spatially repeating textures with potential to be used as gratings.

Rafael Soares Zola

Rafael Soares Zola

UTFPR, Paraná

Possui graduação em Física pela Universidade Estadual de Maringá (2005), mestrado em Física pela Universidade Estadual de Maringá (2007) e doutorado em Liquid Crystals – Kent State University (2012). Atualmente é professor da Universidade Tecnológica Federal do Paraná. Tem experiência na área de Física, com ênfase em Equação de Estado, Equilíbrio de Fases e Transições de Fase, atuando principalmente nos seguintes temas: cristais liquidos, problemas elásticos, Colestéricos, problemas de molhamento e interfaces, desenvolvimento de displays e espectroscopia de impedância. Membro permanente da Pós-Graduação em Ciência dos Materiais (PPGCEM) da UTFPR desde 18/11/2018. Membro permanente da Pós-Graduação em Física da UEM desde 02/02/2014.

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