Physics Colloquium Webinar Series 2022

Science and Technology in Liquid Crystals with Patterned Alignment

Speaker: Hiroyuki Yoshida, Ph.D.
Assoc. Professor
Division of Electrical, Electronic and Information Engineering
Graduate School of Engineering
Osaka University

Moderator: Rahmat Hidayat, Ph.D.

Tuesday, 28 June 2022
13.00 – 14.30 WIB

Abstract

Liquid crystals – materials in which rod-like molecules spontaneously orient along a single direction called the ‘director’– are widely used in electro-optic applications because of their anisotropy and fluidity. In conventional devices such as displays, the liquid crystal is aligned homogenously over a relatively large area, and their tilt angles are controlled to change the birefringence for light propagating through the device. Recently, there is an increasing interest in liquid crystals with patterned alignment, as it confers properties not observed in homogenously-aligned samples. From a materials perspective, patterned alignment enables the control of topological defects, which are singularities in the orientational field [1]. Because topological defects possess viscoelastic properties different from the bulk, and can trap micro- and nano-particles[2], they can be used as templates through which to construct three-dimensional microstructures. From an optical perspective, patterning of the liquid crystal leads to phase modulation of light, not based on refractive index modulation, but through the geometric phase. Because the phase can be modulated by 2π, various planar diffractive optical elements, such as lenses, deflectors, and beam shapers can be fabricated[3-5]. In this presentation, I will review recent works on the science and technology of patterned alignment in liquid crystals.

1) H. Yoshida, K. Asakura, J. Fukuda, and M. Ozaki, Nat. Commun., 6, 7180 (2015).

2) X. Wang, D. S. Miller, E. Bukusoglu, and N. Abbott, Nat. Mater. 15, 106 (2016).,

3) J. Kobashi, H. Yoshida, and M. Ozaki, Nat. Photon., 10, 389-392 (2016).

4) J. Kobashi, H. Yoshida, and M. Ozaki, Phys. Rev. Lett., 116, 253903 (2016).

5) J. Kobashi, H. Yoshida, and M. Ozaki, Sci. Rep. 7, 16470 (2017).