Switchable Bragg diffraction from liquid crystal in colloid-templated structures

Abstract

PACS. 47.20.Dr -Surface-tension-driven instability. PACS. 61.30.Pq -Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems. PACS. 82.70.Dd -Colloids.Abstract. -We have incorporated nematic liquid crystal into periodic, polymer host structures templated from self-assembled colloids. Using these composite materials, we demonstrate the first electrically switchable three-dimensional Bragg diffraction. The switchable beam deflection is potentially useful for non-mechanical beam steering and optical beam splitting devices. We compare the electro-optic response of our templated liquid-crystal/polymer composites with conventional polymer-dispersed liquid crystals (PDLCs). Our data reveal a qualitatively different and faster response for liquid crystal distributed within a connected cavity network, as compared to isolated liquid-crystal droplets within a polymer matrix.c EDP Sciences

Elastic constants, viscosity and response time in nematic liquid crystals doped with ferroelectric nanoparticles

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Engineering liquid crystals for optimal uses in optical communication systems

“…Various techniques have been used to improve these features based, for example, on electromagnetic curing of the LC-monomer mixture [69] or using colloid-templated composites [70]. The addition of surfactants (such as octanoic acids) lowers the switching voltage and improves the diffraction efficiency.…”

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“…Polymer-dispersed liquid crystals (PDLCs) consist of randomly distributed liquid crystal (LC) droplets in a polymer matrix, and result from the phase separation of a LC/prepolymer mixture [1][2][3][4]. When a PDLC film is made with an LC having an extraordinary refractive index (ne) different from the refractive index (np) of the polymer matrix, this refractive index mismatch condition and the randomly distributed optical axes of the droplets leave the PDLC film opaque in its field-off state [5][6][7].…”