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This work demonstrates a polymer-stabilized blue phase (PSBP) liquid crystal phase grating, which is made of hybrid PSBPs with two different Kerr constants. The Kerr constant of a PSBP is related to the morphology of the polymer network which can be controlled by the phase separation temperature. Owing to the non-patterned electrode and the optical isotropy of the PSBP, the diffraction effect can be completely switched off when the voltage is absent. The diffraction intensity increases when a uniform applied electrical field induces the phase difference in the hybrid PSBP. The phase grating is completely independent of the polarization of the incident light. Furthermore, the response time to switching is in the sub-millisecond range. [ABSTRACT FROM AUTHOR]

- In this work, a low-hysteresis polymer-stabilized blue-phase LCD is developed by controlling the polymerization temperature and using a double-sided IPS (DS-IPS) electrode. Compared to a conventional IPS LCD, this DS-IPS LCD has a driving voltage of 45 V, which is lower than that, 62 V, of a conventional single-sided IPS LCD. The transmittance is increased approximately 23%. The hysteresis is reduced to 0.44% which decreases as a function of the operating voltage. Furthermore, simulations of the maximum transmittance and operation voltage associated with the offset between the electrodes in the top and bottom substrates were also evaluated. [ABSTRACT FROM AUTHOR]

This work proposes two mechanisms for switching the direction of stripes in cholesteric liquid crystal (CLC) gratings. The stripe direction depends on the ratio of cell gap to the natural pitch length (d/P0) of a CLC sample. Electrical switching is based on the different pitches at the planar and the transient planar states. Optical switching, however, changes pitch by using the photo-isomerization effect of the azobenzene doped in a CLC sample. Using the two mechanisms, we can switch the stripe directions in two orthogonal directions. Furthermore, the beam-steering capability of CLC gratings also remains effective after switching directions. [ABSTRACT FROM AUTHOR]

Abstract: The study investigates the thermal hysteresis in the phase transition between the cholesteric liquid crystal and the blue phase of liquid crystal. Both the CLC phase and the blue phase can stably exist at room temperature and be switched to each other using temperature-controlled processes. Two sets of bistable conditions are demonstrated using various surface treatments. In a homogeneous aligned sample, two stable states, CLC with a planar alignment and blue phase with a uniform lattice distribution, reflect light of wavelengths 480–510nm and 630nm, respectively, as determined by the corresponding Bragg’s reflection conditions. In the untreated sample, the CLC phase with a focal conic texture can scatter light and the blue phase with a non-uniform lattice distribution provides high isotropic optical transparency. [Copyright &y& Elsevier]

Liquid crystal random fiber lasers (LC-RFLs) exhibit low spatial coherence, extraordinary tunability, and high flexibility and are therefore promising for use in imaging and related applications. They nevertheless suffer from ineffective emission along the fiber axis. This work develops an end-emitting LC-RFL that is based on a pump-induced gain–loss structure, which effectively modulates the optical feedback, thereby providing directional random lasing along the fiber. The laser emission comprises ∼10 000 transverse spatial modes that are mutually incoherent, resulting in a negligible speckle contrast of ∼0.7% (far below the speckle-perception threshold of human eyes). The developed LC-RFL is used to perform speckle-free full-field imaging in a setting with strong optical crosstalk in a multimode fiber. Our findings support the potential widespread use of LC-RFL as a spatially incoherent, flexible laser source. [ABSTRACT FROM AUTHOR]

Abstract: This work studies the biphotonic effect in samples that are cholesteric liquid crystals (CLCs) doped with azo-C5. The experimental results show that the photo-isomerization of azo-C5 not only changes the clearing point of the sample, but also shifts the reflection band that is associated with the planar texture. Additionally, azo dye-doped CLCs (DDCLCs) have bi-stable or tri-stable states, as determined by the ambient temperature. Photo-switching between these bi-stable/tri-stable states is systematically studied. The result indicates that photo-addressing one of these states (planar, focal conic, and isotropic states) using a low- or high-intensity Ar+ laser beam is feasible. The results thus obtained are used to fabricate a photo-rewritable DDCLC display. [Copyright &y& Elsevier]

A superhydrophobic surface that has controllable adhesion and is characterized by the lotus and petal effects is a powerful tool for the manipulation of liquid droplets. Such a surface has considerable potential in many domains, such as biomedicine, enhanced Raman scattering, and smart surfaces. There have been many attempts to fabricate superhydrophobic films; however, most of the fabricated films had uniform adhesion over their area. A patterned superhydrophobic surface with spatially controllable adhesion allows for increased functions in the context of droplet manipulation. In this study, we proposed a method based on liquid-crystal/polymer phase separation and local photopolymerization to realize a superhydrophobic surface with spatially varying adhesion. Materials and topographic structures were analyzed to understand their adhesion mechanisms. Two patterned surfaces with varying adhesion were fabricated from a superhydrophobic material to function as droplet guides and droplet collectors. Due to their easy fabrication and high functionality, superhydrophobic surfaces have high potential for being used in the fabrication of smart liquid-droplet-controlling surfaces for practical applications. [ABSTRACT FROM AUTHOR]