Tunable fly's-eye lens made of patterned polymer-dispersed liquid crystal

Unraveling the Mystery of the Blue Fog: Structure, Properties, and Applications of Amorphous Blue Phase III

The amorphous blue phase III of cholesteric liquid crystals, also known as the "blue fog," are among the rising stars in materials science that can potentially be used to develop next-generation displays with the ability to compete toe-to-toe with disruptive technologies like organic light-emitting diodes. The structure and properties of the practically unobservable blue phase III have eluded scientists for more than a century since it was discovered. This progress report reviews the developments in this field from both fundamental and applied research perspectives. The first part of this progress report gives an overview of the 130-years-long scientific tour-de-force that very recently resulted in the revelation of the mysterious structure of blue phase III. The second part reviews progress made in the past decade in developing electrooptical, optical, and photonic devices based on blue phase III. The strong and weak aspects of the development of these devices are underlined and criticized, respectively. The third- and-final part proposes ideas for further improvement in blue phase III technology to make it feasible for commercialization and widespread use.

Low-threshold, single-mode, and linearly polarized lasing from all organic quasicrystal microcavity

Organic microcavity lasers based on liquid crystals have attracted substantial attention due to their easy processing, compact volume and excellent tunable properties. However, the threshold of traditional holographic polymer dispersed liquid crystals (H-PDLCs) laser doped with dye is usually as high as several tens of μJ/pulse, which hinders its broad applications. Herein, we demonstrate a low-threshold lasing from quasicrystal based on H-PDLCs. An conjugated polymer poly (2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylenevinylene (MEH-PPV) film is coated on the inner surface of glass substrate to dramatically reduce the lasing threshold, which is 20 times lower than that of dye-doped microcavity laser. A low threshold, single-mode, linearly polarized lasing is achieved when the thickness of MEH-PPV film is optimized at 80 nm. Due to its easy fabrication, excellent performance and bio-compatibility, this compact coherent light source may be useful in lab-on-chip applications such as detection, sensing and analyzing, as well as display, optical communications, and other photonic fields.

Characteristics of color optical shutter with dye-doped polymer network liquid crystal

The optical properties and the theoretical prediction of color optical shutter with dye-doped polymer network liquid crystal (PNLC) were investigated. The view-angle dependence of reflectance according to the bias conditions showed distinctive characteristics, which could be explained from the effects of dye absorption and path length. It was also shown that the thickness dependence of reflectance was strongly influenced by the light-scattering coefficient. Our experimental results matched up well with the theoretical prediction based on the light scattering of liquid crystals in polymer network and the absorption of dichroic dye. This work indicates potential to improve the optical device using dye-doped liquid crystal-polymer composite.

Airy beams generated by a binary phase element made of polymer-dispersed liquid crystals

Using polymer-dispersed liquid crystals (PDLCs), an electrically switchable binary phase pattern was fabricated to generate Airy beams through a programmable lithographic system. The right main lobe of the reconstructed Airy beam experienced 1.3 mm transverse deflection within 24 cm propagation distance. With a suitable voltage applied, the binary PDLC pattern can be erased due to the index match between polymers and liquid crystals. This versatile approach can be also used to generate other special beams with electrically tunable capability.

Electrically switchable phase-type fractal zone plates and fractal photon sieves

Electrically switchable phase-type fractal zone plates and fractal photon sieves were fabricated using polymer-dispersed liquid crystal material based on a photomask. While both exhibited similar first-order diffraction behavior, the fractal photon sieves showed greatly suppressed diffraction at higher orders. Compared with current amplitude-type photomasks, our switchable, phase-type devices demonstrated higher diffraction efficiency, an important factor in the future development of adaptive optics.

A negative-positive tunable liquid-crystal microlens array by printing

A tunable microlens array by printing was demonstrated. An UV-curable adhesive, NOA65, was printed and cured to form a lens array profile on an ITO glass. Then this microlens array ITO glass was assembled with a normal ITO glass to form a cell, which was later filled with a liquid crystal. The focal length of the lens array can be tuned by an electric field, which changes the index difference between liquid crystals and NOA65 due to the reorientation of the LC molecules. In our experiment, the focal length varied from -2.29 cm to 3.12 cm when the applied voltage was increased from 0 V to 13.26 V.

Liquid-crystal materials find a new order in biomedical applications

With the maturation of the information display field, liquid-crystal materials research is undergoing a modern-day renaissance. Devices and configurations based on liquid-crystal materials are being developed for spectroscopy, imaging and microscopy, leading to new techniques for optically probing biological systems. Biosensors fabricated with liquid-crystal materials can allow label-free observations of biological phenomena. Liquid-crystal polymers are starting to be used in biomimicking colour-producing structures, lenses and muscle-like actuators. New areas of application in the realms of biology and medicine are stimulating innovation in basic and applied research into these materials.