Ji-Liang Zhu

1D/2D switchable grating based on field-induced polymer stabilized blue phase liquid crystal

We present a 1D/2D switchable grating based on field-induced polymer stabilized blue phase liquid crystal (PSBPLC). For 1D grating, the diffraction efficiency of the first order is 37.2% and the phase modulation depth of the 1D grating can achieve 2π. For 2D grating, more than 90% of light intensity is distributed to the surrounding orders of zero order and the phase modulation depth is about 3.67π. Furthermore it shows fast phase modulation and 1D/2D switching time.

The Influence of polymer system on polymer-stabilised blue phase liquid crystals

The influence of polymer system on polymer-stabilised (PS) blue phase (BP) liquid crystal (LC) is investigated. After polymer stabilisation, anchoring energy appears between the polymer network and LC molecules, which is related with the stiffness of the polymer system. As the stiffness of polymer system decreases, the Kerr constant can be improved with the degradation of response time, hysteresis, and residual birefringence. Furthermore, the Kerr constant and response time can be improved simultaneously by polymer system with reactive diluents.

Improved Kerr constant and response time of polymer-stabilized blue phase liquid crystal with a reactive diluent

A polymer-stabilized (PS) blue phase liquid crystal (BPLC) with fast response time and large Kerr constant is investigated by doping a low molecular weight monomer (N-vinylpyrrollidone) into a conventional PS-BPLC consisting of BPLC, RM257, and 1,1,1-trimethylolpropane triacrylate. With this polymer network system, Kerr constant and the response can be improved simultaneously. Compared to the conventional PS-BPLC, Kerr constant of the proposed PS-BPLC can increase by 54% and the response time can decrease by 23% at the same time. The contrast ratio can be kept at a high level, over 1000:1 at λ = 633 nm.

Blue Phase LC/Polymer Fresnel Lens Fabricated by Holographics

A novel fabrication method using holographic exposure for switchable blue phase (BP) liquid crystal (LC)/polymer Fresnel lens was demonstrated. The Fresnel pattern can be achieved by interfering a planar and a spherical wave fronts with a 532-nm laser. The BPLC/polymer Fresnel lens can thus be fabricated without photo mask and controlled with a simpler driving compared with the conventional LC Fresnel lens.

Low-voltage blue-phase liquid crystals with polyaniline-functionalized graphene nanosheets

A small amount of polyaniline functionalized graphene (G–PANI, 0.03–2.00%) nanosheets was doped into conventional polymer-stabilized blue phase liquid crystals (PS-BPLCs), and the electro-optical property effects were studied. The driving capability of BPLCs can be much improved in that the Kerr constant of BPLCs doped with 0.05 wt% G–PANI is increased by ∼55% compared with that of BPLCs without G–PANI. Meanwhile, this composite exhibits no degradation of electro-optical properties, such as response time, hysteresis and residual birefringence.

Critical temperature in phase transition of blue phase liquid crystal

A critical temperature is found in the phase transition of blue phase liquid crystal (BPLC), which affects the electro-optical properties and polymer stabilization of polymer stabilized BPLCs (PSBPLCs). The relation between lattice formation process of BPLCs and the temperature is also demonstrated showing that the heterogeneous lattice generation and the homogeneous lattice growth dominate the different temperature ranges in phase transition process. With different cooling rates, the material properties of BPLCs change as the result of different stages of heterogeneous lattice generation and homogeneous lattice growth.

Chiral-induced self-assembly sphere phase liquid crystal with fast switching time

A fluid self-assembly sphere phase (SP) of liquid crystal induced by chiral dopant is observed in a narrow temperature range between isotropic and blue phase or between isotropic and chiral nematic phase. The SP consists of three-dimensional twist spheres (3-DTSs) and disclinations among 3-DTSs. The temperature range of the SP has been broadened to more than 85 °C by stabilizing the disclinations with amorphous polymer chains. The electro-optical switching time of the polymer-stabilized SP is demonstrated in sub-millisecond with a low switching electric field of 4.4 V μm−1, which is of promising applications in displays, 3-D tunable photonic crystals, and phase modulators.

A Transflective Display Using Blue Phase Liquid Crystal

A combined fringe and in-plane switching (FIS) mode single-cell-gap transflective display using blue-phase liquid crystal (BPLC) is proposed. The structure makes use of the space above the pixel electrodes of this FIS mode as reflective regions and the space between pixel electrodes as transmissive regions. The structure which can be optimized to balance the optical phase retardation between transmissive region and reflective region with simple fabrication process exhibits relatively high optical efficiency and well matched voltage of transmittance and reflectance curves.