Jiangang Lu

2-D/3-D Switchable Display by Fresnel-Type LC Lens

We demonstrate a multi-electrode Fresnel-type 2-D/3-D switchable display with electrically controlled birefringence mode liquid crystal (LC) lenses. By applying a discontinuous nonuniform electric field, the display with this structure can form a Fresnel-type refractive-index distribution to generate 3-D images. Compared to a normal LC lens, the Fresnel-type LC lens can achieve faster switching speed for dynamic applications. It can also replace the high sag solid lens for 3-D applications with relatively small cell gap. Furthermore, a Fresnel lens with suitable refractive-index profile is proposed to reduce the crosstalk in the 3-D displays.

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.

Video-Rate Holographic Display Using Azo-Dye-Doped Liquid Crystal

A video-rate optical holographic display is achieved by using an azo-dye-doped liquid crystal as the passive, updatable recording material. The response time of this material is measured in the order of several to tens of milliseconds, depending on recording beam intensities, polarization directions, and polarization states. A holographic video at a refresh rate of 25 Hz, sourced from a spatial light modulator, is demonstrated in the experiments.

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.

Polymer-stabilized blue-phase liquid crystal grating cured with interfered visible light

In this paper, we demonstrate a holographic polymer-stabilized blue-phase liquid crystal grating fabricated using a visible laser. As blue phase is stabilized by the interfered light, polymer-concentration gradient is achieved simultaneously. With the application of a uniform vertical electric field, periodic index distribution is obtained due to polymer-concentration gradient. The grating exhibits several attractive features such as polarization-independency, a broad temperature range, sub-millisecond response, simple fabrication, and low cost, thus holding great potential for photonics applications.

Random laser emission in a sphere-phase liquid crystal

We investigated random lasing from a fluid self-assembly sphere-phase liquid crystal, which was composed of three-dimensional twist sphere structures with disclinations among them. The threshold energy of the random lasing from sphere-phase liquid crystal was 32% of that from the chiral nematic phase because of the interference associated with multiple scattering by randomly distributed sphere-phase platelets. Such random lasers composed of self-assembly soft organic materials may be useful for holographic displays, point-of-care biomedical analysis, and optical security coatings.

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.

High-transmittance polymer-stabilised blue-phase liquid crystal display with double-sided protrusion electrodes

A polymer-stabilised blue-phase liquid crystal display (PSBP-LCD) with double-sided protrusion (DSP) electrodes structure is proposed. The oblique electric field between the protrusion electrodes inside both top and bottom glass substrates can induce more isotropic-to-anisotropic transition in the polymer-stabilised blue-phase liquid crystal (PS-BPLC) medium through Kerr effect than using the in-plane switching electrode. For the same electrode width, spacing and cell gap, the transmittance of PSBP-LCD with the DSP electrodes is ∼29% higher than that using the IPS electrode.

High directional backlight using an integrated light guide plate.

A high directional backlight system that combined a composite microstructure light guide plate (LGP) with a collimated light source was proposed for eco-displays. The collimated planar light was expanded from a point light source and guided towards the normal direction by utilizing the micro-prism array on LGP. High uniformity of spatial luminous, 91%, with a narrow viewing cone of ± 4° can be achieved without additional optical films. Moreover, compared to the conventional backlight, only 5% of power consumption was needed to keep the same luminance, hence, the optical efficiency increased by a factor of 1.47.