Electrically switchable polymer membranes with photo-aligned nematic structures for photonic applications

• Published in: Optical materials 2020-11, Vol.109, p.110296, Article 110296
• Main Authors: Dubtsov, Alexander V., Harkai, Saša, Shmeliova, Dina V., Pasechnik, Sergey V., Repnik, Robert, Chigrinov, Vladimir G., Kralj, Samo
• Format: Article
• Language: English
• Subjects: Electro-optical response; Nematic microstructures; Optical textures; Photoalignment; Photonic LC elements; Polymer membranes
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2020.110296

Composite materials containing liquid crystalline microstructures, providing fast stimuli responsive variations of birefringence at low consumption power, have great potential applications in photonics. Here, a composite material based on polymer membranes with photo-aligned nematic microstructures is proposed for the first time. For this purpose, porous polyethylene terephthalate (PET) films were covered with an azo-dye and subjected to a modified photoalignment technique to control the azimuthal orientation and anchoring strength of nematic liquid crystals (LCs) at the pore walls. Nematic internal ordering was identified using polarized optical microscopic observations assisted by theoretical simulations. The proposed approach provides spatial distribution of nematic microstructures characterized by specific internal ordering and fingerprint in near infrared spectra at an electro-optical response. These composites can be used as flexible photonic LC elements such as spatial light modulators, optical filters and lenses. [Display omitted] •New composite material containing liquid-crystalline microstructures is proposed.•Liquid crystals are photo-aligned within the porous membranes for the first time.•Photoalignment technique is successfully modified for porous polymer membranes.•Different nematic configurations are realized within the porous film.•Photopatterned nematics tune an electro-optical response of the composite film.