Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves

Polymer-stabilized optically isotropic liquid crystals, including blue phases, are emerging as a strong contender for next-generation display technology because they exhibit some revolutionary features such as no need for surface alignment, submillisecond response time, isotropic dark state, and cell gap insensitivity. The basic material properties, including electric field-induced birefringence, dispersion relation of Kerr constant, and temperature dependent Kerr constant, are reviewed. Recent progress on blue phase liquid crystal material development and device structures for lowering the operating voltage are introduced. Promising applications and remaining technical challenges are also discussed.

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Polymer-stabilized optically isotropic liquid crystals for next-generation display and photonics applications

A polymer-stabilized blue phase liquid crystal (BPLC) composite with a large Kerr constant (K∼13.7 nm/V2) is developed and its electro-optic properties characterized. In addition to the reduced operating voltage, this BPLC also exhibits a fast response time (∼1 ms), high contrast ratio (>1000:1), and relatively small hysteresis (<6%). It will undoubtedly accelerate the emergence of BPLC for next-generation display and photonic devices.

/pdf/a-large-kerr-constant-polymer-stabilized-blue-phase-liquid-34kcaubp0w.pdf

A large Kerr constant polymer-stabilized blue phase liquid crystal

We demonstrate a tunable phase grating using a polymer-stabilized blue phase liquid crystal Because of the electric-field-induced rectangularlike phase profile, a high diffraction efficiency of 40% is achieved Moreover, this device shows submillisecond response time The proposed tunable phase grating holds great potential for photonics and display applications

/pdf/high-efficiency-and-fast-response-tunable-phase-grating-n4osxijnnu.pdf

High-efficiency and fast-response tunable phase grating using a blue phase liquid crystal.

Lenses with tunable focal length play important roles in nature by helping species avoid predators and capture prey. Many practical devices mimic lens concept for imaging, sensing, and detection. This review covers fundamental optics of lenses and its extension to lenses made of liquid crystals (LCs). Three main types of LC lenses are described, namely, lenses with curved surfaces, flat gradient-index lenses and composite lenses. The review discusses advantages of LC lenses over their isotropic counterparts, challenges in their fabrication and control, as well as a variety of potential applications. We also discuss the current challenges associated with nematic LC lenses and their solutions. LC lenses are already having significant impacts on optics and optometry, and these impacts will grow with discovering new LC materials and new lens designs.

Liquid crystal lenses with tunable focal length

We demonstrate polarizer-free and fast response microlens arrays based on optical phase modulation of polymer-stabilized blue phase liquid crystal (PSBP-LC). Polarization-independent optical phase shift is because the propagation of an incident light is along the optic axis of PSBP-LC, and birefringence of PSBP-LC induced by Kerr effect results in electrically tunable optical phase shift. The measured optical phase shift of a PSBP-LC phase modulation is around π radian at 150 Vrms for the cell gap of 7 μ. The response time is about 3 ms. The focal length is around 13.1 cm at 100 Vrms.

https://ir.nctu.edu.tw:443/bitstream/11536/5706/1/000275825200066.pdf

Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals

We demonstrate a hysteresis-free polymer-stabilized blue phase liquid crystals (PSBP-LCs) using thermal recycles by means of enlarging the domain size of PSBP-LC and improving the uniformity of the crystal orientations of PSBP-LC. The crystal growth of PSBP-LCs bases on a competition between the heterogeneous nucleation and the homogeneous nucleation is also demonstrated and discussed. This study opens a new window for understanding the hysteresis of the PSBP-LC and assisting in designing many PSBP-LC-based photonic devices, such as displays, electro-optical switches, and electrically tunable focusing LC lenses.

https://ir.nctu.edu.tw:443/bitstream/11536/16602/1/000307117600019.pdf

Hysteresis-free polymer-stabilized blue phase liquid crystals using thermal recycles

A bistable, polarizer-free, and reflective electro-optical switch based on a droplet manipulation on a liquid crystal and polymer composite film (LCPCF) is demonstrated. A color droplet on LCPCF can be manipulated by a wettability gradient owning to the distribution of LC directors anchored among the polymer grains on LCPCF. The contrast ratio is around 8:1 in a reflective mode. The potential applications of droplet manipulation are electronic papers and reflective displays.

https://ir.nctu.edu.tw:443/bitstream/11536/5413/1/000277560000036.pdf

A bistable polarizer-free electro-optical switch using a droplet manipulation on a liquid crystal and polymer composite film

We demonstrate a reflective polarizer-free electro-optical switch using dye-doped polymer-stabilized blue phase liquid crystals (DDPSBP-LC). At the voltage-off state, the dye molecules and liquid crystals form the structure of the double twist cylinders. As a result, the DDPSBP-LC is in dark state due to the combination of Bragg reflection and light absorption. At the voltage-on state, the blue phase structure is unwound locally. The DDPSBP-LC is then in bright state because of the small light absorption only. The applications of such a switch are shutter glass of 3D displays, and electronic papers.

https://ir.nctu.edu.tw:443/bitstream/11536/25862/1/000286807100095.pdf

A reflective polarizer-free electro-optical switch using dye-doped polymer-stabilized blue phase liquid crystals.

A simple optical method to measure the electric-field-induced birefringence and Kerr constant of polymer-stabilized blue-phase liquid crystals (PSBP-LC) is demonstrated. By measuring the phase shift of PSBP-LC and the averaged refractive index of PSBP-LC at the voltage-off state, the ordinary refractive index and extraordinary refractive index of PSBP-LC as function of applied voltage can be obtained experimentally. As a result, the electric-field-induced birefringence and Kerr constant can be determined as well. The method we proposed can help in designing PSBP-LC–based photonic devices.

https://ir.nctu.edu.tw:443/bitstream/11536/8855/1/000292115900132.pdf

Hsu Kuan Hsu

Papers

Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals

Hysteresis-free polymer-stabilized blue phase liquid crystals using thermal recycles

A bistable polarizer-free electro-optical switch using a droplet manipulation on a liquid crystal and polymer composite film

A reflective polarizer-free electro-optical switch using dye-doped polymer-stabilized blue phase liquid crystals.

Measuring electric-field-induced birefringence in polymer stabilized blue-phase liquid crystals based on phase shift measurements