The photograph shows a polymer reflector that mimics the colour and underlying molecular structure of a golden beetle. It is formed from self-organizing layers of photopolymerised liquid crystal. These require an aligning layer, but we show that a layer of the material can be used as to self-align subsequent coatings, enabling the construction of complex structures by sequential coating of engineered materials.

The interest in the application of cholesteric liquid crystals for tunable lasers has risen in the past few years. Here, we want to obtain a mechanically tunable laser device using cholesteric liquid crystal (CLC) elastomers as resonant cavity mirrors in a three-layer configuration, which includes in between an isotropic layer incorporating a laser dye as active medium. The transmission band-gap of the two CLC elastomers was shifted one with respect to the other in order to create a defect ("notch") in the middle of the band-gap which allowed a single-mode lasing from the system. The wavelength of the laser could be changed by mechanical tuning of the rubbery device.

A new tuning strategy for mirror-less liquid crystals laser is presented. A three layer cell is prepared with two cholesteric layers sandwiching a layer containing an isotropic mixture of a photoluminescent dye. One of the chiral layers contains a wide band gap material while the second layer consists of a series of small band gap materials. Through the combination of these two layers, a set of mirrors that can selectively reflect different wavelengths is obtained. A different laser wavelength is emitted from different regions of the cell under the pumping beam irradiation.

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