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Chameleons, which are among the poikilotherms, can rapidly change color for camouflage, communication and thermoregulation. These cold-blooded animals physiologically shift color through the active tuning of lattices of guanine nanocrystals within a superficial thick layer of dermal iridophores. This active tuning can be described as alternating different refractive indices of nano-reflectors, thereby generating interference of light waves. The self-regulation of the skin behind its dynamic color changing ability makes it the ultimate “biomimetic surface” and a continued source of inspiration. We presented a deformation-color multi-responsive actuator whose response is controlled by delicate light to mimic these adaptive functions. This soft smart material is developed by well-aligned cholesteric liquid crystal elastomers (CLCE). It performs a 185 nm wavelength shift of selective reflection and is switched by reacting to exposure time. Effective optical management is critical for the operation of many modern technologies. These results demonstrate distinctive potential opportunities for LC elastomers to control light, thereby enabling new applications of modern technologies to textiles, optics, and architecture.

This study demonstrates a broadband-tunable photonic bandgap (PBG) and thermally convertible laser with an ultra-low lasing threshold based on a gradient-pitched cholesteric liquid crystal (CLC) polymer template. The lowest energy threshold of the laser is 16 nJ per pulse under a pumped diameter of ca. 250 μm (i.e., 0.33 μJ per pulse per mm2), a value that is superior to those of other band-edge lasers based on most dye/quantum-dot-doped CLC systems. Owing to its multiple advantages, such as high stability, ultra-low lasing threshold, wide-band and linear spatial PBG-tunability, and lasing-mode convertibility, the CLC template device can be potentially used for photonics and display applications.

This work fabricates a fishnet grating by exerting two one-dimensional (1D) holographic interference fields with mutually orthogonal grating vectors separately on the substrates of a dye-doped liquid crystal (DDLC) cell. The DDLC mixture in the cell includes a nematic LC, methyl red (MR) dye, and 4-methoxyazobenzene (4MAB) dye. The fishnet grating is formed because the periodical adsorption of the MR dye on the irradiated surfaces of the cell causes the anisotropic photoalignment of the LC. The fishnet grating can be erased (recovered) by the illumination of a UV (green) beam since the trans → cis (cis → trans) isomerization of the 4MAB dye causes the isothermal nematic → isotropic (isotropic → nematic) phase transition of the LC. Such a grating can be used to develop optically controllable photonic crystals. Simulated results depict that a photoresist-coated plastic substrate that is exposed to the fishnet pattern of a 2D grating can be used to develop terahertz fishnet metamaterials, and their resonance spectra can be passively tuned by moving the substrate and lens that forms the fishnet pattern during fabrication. Therefore, the mask-free photolithography can be used to fabricate passively tunable terahertz filters.

Dye-doped nematic liquid crystal refilled gradient-pitched enantiomorphic cholesteric liquid crystal polymer templates are demonstrated. The enantiomorphic device has high reflectivity and wide spectral tunability throughout the entire visible region. This device can also provide low threshold lasing emission with both right- and left-circular polarizations from the blue to the red region.

This investigation is the first report of an optically stable and tunable laser using a quantum-dot (QD) embedded cholesteric liquid crystal (QD-CLC) microresonator with an added chiral-azobenzene moiety. The QD nanocrystal, CLC, and chiral-azobenzene play key roles in the highly stable fluorescence nano-emitter, microresonator, and photo-tuner in the photonic bandgap (PBG) of the CLC and associated lasing output, respectively. Experimental results show that both the PBG and lasing emission of the QD-CLC composite sample can be reversibly tuned under successive irradiation with UV and blue beams. The all-optical tunability of the laser is attributed to the successive elongation and shrinkage of the CLC pitch induced by UV- and blue beam-irradiation induced trans–cis and cis–trans back isomerizations of chiral-azobenzene, respectively. In addition, this composite laser has a high damage threshold (>85 μJ per pulse), and thus shows a uniquely high optical stability. This work has successfully opened up an opportunity for developing QD coherent light sources or lasers with good optical stability and tunability (e.g., optically stable and tunable single photon lasers).