Liquid-crystal-based fiber laser sensor for non-invasive gas detection

This Letter reports a new optical fiber gas sensor for measuring breath acetone. The sensor is based on photonic bandgap (PBG) mode laser emission sensing technology using liquid crystal (LC), which is combined with silica fiber and chiral nematic liquid crystal (CNLC), thus providing an ultra-compact, fast-response and simple-to-produce sensing system with a fast response that can accurately and quantitatively determine the concentration of respiratory acetone within the normal oral temperature range (35-38°C). Since LCs are affected by temperature, we propose a method that eliminates the influence of the temperature to solve the problem of the temperature influence when measuring gas. The detection of acetone leads to splitting of the dual laser peaks, with a linear correlation of 0.99. The sensor has a limit of detection of 65 ppm for acetone vapor and thus is suitable for breath acetone detection in diabetic patients.

Allyl sulfide-based visible light-induced dynamically reshaped liquid crystalline elastomer/SWCNT nanocomposites capable of multimode NIR photomechanical actuations

The fully light-driven LCE/SWCNT composite films with exchangeable covalent crosslinks possess reconfigurability and recyclability, enabling shrinking, bending and curling motions.

Overcoming repetition rate limitations in liquid crystal laser systems

Liquid crystal lasers have advantageous features, including continuous wavelength tuning at low cost. Although many potential applications have been highlighted, use of these lasers is not widespread, partially due to performance limitations. This paper presents a method of overcoming repetition rate limitations. A rapidly spinning stage is used to allow operation of a LC laser at 10 kHz: two orders of magnitude greater than possible with a static cell. Average power outputs of up to 3.5 mW are achieved along with an improvement in emission stability. Lastly, a mechanical wavelength-switching method is demonstrated. The spinning cell approach will enable research into the use of liquid crystal lasers in fluorescence imaging and display applications.