Conventional polymer dispersed liquid crystal (PDLC) films have been successful as electrically‐switchable screens for privacy applications. However, spatial patterning of the films so as to generate a visually appealing design, logo, or image typically requires intricate fabrication processes, such as the use of prefabricated photomasks that do not allow for on‐demand designs. Herein is reported on the fabrication and characterization of spatially patterned PDLC “pixels” using drop‐on‐demand inkjet printing, and it is demonstrated how these materials can be used to form a new generation of smart windows that consist of embedded images or company logos, which can be made to disappear with the application of a voltage. Following refinements to the material rheology and the subsequent successful deposition of individual PDLC droplets, arrays of PDLC pixels are printed at a resolution of 250 pixels per inch with an individual pixel size of 130 µm operating at an electric field strength (E) of E = 1.4 V μm⁻¹. Finally, using the approach developed herein, these printed PDLC pixels are arranged to form a college emblem that is embedded within a smart window that can be made to disappear with the application of a voltage.

The photonic color-changing function of chameleons can be achieved by bionic soft-active photomechanochemically responsive cholesteric liquid crystal elastomers.

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).

This investigation elucidates for the first time electrically controllable random lasers below the threshold voltage in dye-doped liquid crystal (DDLC) cells with and without adding an azo-dye. Experimental results show that the lasing intensities and the energy thresholds of the random lasers can be decreased and increased, respectively, by increasing the applied voltage below the Fréedericksz transition threshold. The below-threshold-electric-controllability of the random lasers is attributable to the effective decrease of the spatial fluctuation of the orientational order and thus of the dielectric tensor of LCs by increasing the electric-field-aligned order of LCs below the threshold, thereby increasing the diffusion constant and decreasing the scattering strength of the fluorescence photons in their recurrent multiple scattering. This can result in the decrease in the lasing intensity of the random lasers and the increase in their energy thresholds. Furthermore, the addition of an azo-dye in DDLC cell can induce the range of the working voltage below the threshold for the control of the random laser to reduce.

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This study investigates, for the first time, an all-optically controllable random laser based on a dye-doped liquid crystal (DDLC) cell added with a photoisomerizable dye. Experimental results indicate that the lasing intensity of this random laser can be all-optically controlled to decrease and increase sequentially with a two-step exposure of one UV and then one green beam. All-optically reversible controllability of the random lasing emission is attributed to the isothermal nematic(N)→isotropic(I) and I→N phase transitions for LCs due to the UV-beam-induced trans→cis and green-beam-induced cis→trans back isomerizations of the photoisomerizable dye, respectively. The former and the latter can decrease and increase the spatial fluctuations of the order and thus of the dielectric tensor of LCs, respectively, subsequently increasing and decreasing the diffusion constant (or transport mean free path), respectively, and thus decaying and rising the scattering strength for the fluorescence photons in their recurrent multi-scattering process, respectively. The consequent decrease and increase of the lasing intensity for the random laser and thus the rise and descent of its energy threshold are generated, respectively.