Article, 2024

Spatial Photo‐Patterning of Nematic Liquid Crystal Pretilt and its Application in Fabricating Flat Gradient‐Index Lenses

Advanced Materials, ISSN 1521-4095, 0935-9648, Volume 36, 23, Page e2310083, 10.1002/adma.202310083

Contributors

Modin, Alvin 0000-0002-1195-1368 (Corresponding author) [1] Leheny, Robert L [1] Serra, Francesca 0000-0002-7308-7616 (Corresponding author) [1] [2]

Affiliations

  1. [1] Johns Hopkins University
    2. [NORA names: United States; America, North; OECD];
  2. [2] University of Southern Denmark
    3. [NORA names: SDU University of Southern Denmark; University; Denmark; Europe, EU; Nordic; OECD]

Abstract

Liquid crystals offer a dynamic platform for developing advanced photonics and soft actuation systems due to their unique and facile tunability and reconfigurability. Achieving precise spatial patterning of the liquid crystal alignment is critical to developing electro-optical devices, programmable origami, directed colloidal assembly, and controlling active matter. Here, a simple method is demonstrated to achieve continuous 3D control of the directions of liquid crystal mesogens using a two-step photo-exposure process. In the first step, polarized light sets the orientation in the plane of confining substrates; the second step uses unpolarized light of a prescribed dose to set the out-of-plane orientation. The method enables smoothly varying orientational patterns with sub-micrometer precision. As a demonstration, the setup is used to create gradient-index lenses with parabolic refractive index profiles that remain stable without external electric fields. The lenses' focal length and sensitivity to light polarization are characterized through experimental and numerical methods. The findings pave the way for developing next-generation photonic devices and actuated materials, with potential applications in molecular self-assembly, re-configurable optics, and responsive matter.

Keywords

active matter, actuation system, actuator materials, alignment, applications, assembly, colloidal assembly, control, crystal, crystal alignment, demonstration, devices, direction, dose, dynamic platform, electric field, electro-optical devices, external electric field, fabrication, facile tunability, field, findings, focal length, gradient-index lenses, index profile, length, lenses, light, light polarization, liquid crystal alignment, liquid crystal mesogens, liquid crystals, materials, matter, mesogens, method, molecular self-assembly, next-generation photonic devices, numerical method, optics, orientation, orientation patterns, origami, out-of-plane orientation, parabolic refractive index profile, patterns, photo-exposure process, photonic devices, photons, plane, platform, polarization, precision, prescribed dose, pretilt, process, profile, reconfiguration, refractive index profile, self-assembly, sensitive to light polarization, sensitivity, setup, soft actuation system, spatial patterns, sub-micrometer precision, substrate, system, tunability, unpolarized light

Funders

  • United States-Israel Binational Science Foundation
  • Directorate for Mathematical & Physical Sciences
  • Division of Materials Research

Data Provider: Digital Science

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