Soo-Seok Choi

Electrically controlled color tuning of the photonic bandgap and electrically induced multiple photonic bandgaps from a chiral nematic liquid crystal mixture doped with a ferroelectric liquid crystal. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any

Structural color can be produced by nanoperiodic dielectric structures using soft materials. Chiral photonic elastomers (CPEs) produced from elastic chiral liquid crystal molecules can self-organize into a helical nanostructure, and the chiral nanostructural color can be tuned by stretching. However, the ability to control the separation of biomimetic multicolors for practical applications beyond simple uniaxial stretching of single-colored structures has been limited until now. Here, stretchabl

Abstract Chiral liquid crystal elastomers (CLCEs) are soft photonic materials that exhibit both the photonic characteristics of nanoscale periodic helical structures and mechanical properties of rubber. Owing to its elasticity, the structural color of CLCEs can be tuned through mechanical deformations known as mechanochromism. Thus far, there is significant research attention to exploring the mechanochromism of CLCEs. However, most studies have only discussed the color shifting of CLCEs under un

A broad and fast wavelength tuning of the photonic bandgap of a hybrid photonic band structure (PBS) formed from an achiral nematic liquid crystal and a polymer template. Remarkably, red-green-blue reflection from a single device and a single achiral nematic liquid crystal mixture is reported without any additional optical components such as a color filter.

Contractors responsible for the whole execution of engineering, procurement, and construction (EPC) projects are exposed to multiple risks due to various unbalanced contracting methods such as lump-sum turn-key and low-bid selection. Although systematic risk management approaches are required to prevent unexpected damage to the EPC contractors in practice, there were no comprehensive digital toolboxes for identifying and managing risk provisions for ITB and contract documents. This study describ

In this letter, the authors demonstrate photonic band gap (PBG) tuning in chiral nematic liquid crystals using electrically commanded surfaces consisting of a ferroelectric liquid crystal. The electrically commanded surfaces generate a contraction of the pitch of the chiral nematic which is manifested as a blueshift of the PBG. Results are presented which demonstrate that tuning can be achieved by either varying the frequency or the amplitude of the electric field. The maximum shift observed for

In this paper, we describe in detail the electrical photonic band gap (PBG) tuning properties of a chiral nematic liquid crystal (N*LCs) using electrically active ferroelectric liquid crystals (FLCs) to generate surface mediated switching. The tuning of the PBG occurs as a result of a contraction of the helix which is induced passively by the in-plane rotations of the N*LC molecules at the FLC/N*LC interface. We provide detail on the preparation of the samples and discuss how the tuning range is

Chiral photonic-band structure provides technical benefits in the form of a self-assembled helical structure and further functional wavelength tunability that exploits helical deformation according to pitch changes. The stopband wavelength control of the chiral photonic-band structure can be obtained by individual electrical methods or mechanical stretching deformation approaches. However, research on combined electric control of stretchable chiral photonic-band wavelength control while ensuring

In contrast to nano-processed rigid photonic crystals with fixed structures, soft photonic organic hydrogel beads with dielectric nanostructures possess advanced capabilities, such as stimuli-responsive deformation and photonic wavelength color changes. Recenlty, advanced from well-investigated mechanochromic method, an electromechanical stress approach is used to demonstrate electrically induced mechanical color shifts in soft organic photonic hydrogel beads. To better understand the electrical

The growing demand for cryptographic security encourages the innovation of advanced materials with unique optical properties to secure information using light. Structural colors with soft materials exhibit dynamically tunable optical properties in response to external stimuli, making them ideal for multi-level photonic encryption. However, most previous studies on structural color-based photonic encryption have predominantly focused on single-wavelength tuning while employing inadequate triggeri

Abstract Stretchable structural color technologies are garnering significant attention in photonics for various applications owing to its stretchable flexibility and ability to control the photonic wavelength of light. However, stretchable photonic media, such as chiral liquid crystal elastomers (CLCEs), are subjected to uncontrollable nonuniform strain distribution and position‐dependent color change during the stretching‐assisted color tuning process. Therefore, controlling the colors of the m

Wavelength-tunable structural colors using stimuli-responsive materials, such as chiral liquid crystals (CLCs), have attracted increasing attention owing to their high functionality in various tunable photonic applications. Ideally, on-demand omnidirectional wavelength control is highly desirable from the perspective of wavelength-tuning freedom. However, despite numerous previous research efforts on tunable CLC structural colors, only mono-directional wavelength tuning toward shorter wavelength

To design the multilayered structures of reliable rollable displays, finite element method (FEM) investigations are conducted at various rolling conditions. Given that the optically clear adhesive (OCA) is the only flexible component and interfacial layer that plays an important role in allowing flexibility in rollable displays, we investigated its nonlinear elastic properties in detail. Hereto, FEM of rollable displays have been limited and inaccurate because OCA has been assumed to be a linear

A liquid crystal device is demonstrated using a short-pitch (260 nm) chiral nematic with negative dielectric anisotropy. Due to dielectric coupling, an in-plane electric field switches the liquid crystal between the standing-helix (field-off, “dark” state) and lying-helix (field-on, transmissive state) configurations. We report experimental results on the optical transmission as a function of the applied field, the response time (as short as 35 microseconds) and the contrast ratio (1000:1).

We present experimental results on the bulk flexoelectric coefficients e and effective elastic coefficients K of non-symmetric bimesogenic liquid crystals when the number of terminal and lateral fluoro substituents is increased. These coefficients are of importance because the flexoelastic ratio e/K governs the magnitude of flexoelectro-optic switching in chiral nematic liquid crystals. The study is carried out for two different types of linkage in the flexible spacer chain that connects the sep