• Energy Research

We present the results of the spectral transmittance and reflectance of a SiO2/TiO2 1D photonic crystal deposited by Radio Frequency sputtering on a flexible polymeric substrate, which shows a blue-shift in its transmittance stopband proportional to the incidence angle when bent. An adjustable sample holder was designed to regulate the bending and keep the sample in a bent condition. Different angles of incidence were also achieved through variable angle reflectance, where an increase in incidence angle led to the blue-shift and narrowing of the transmittance stopband. We addressed the sample's resistance against bending wear and tear by comparing the transmittance spectra acquired for the flat sample before and after the measurements made in bent configurations. An important stability has been observed.

Thin films have a crucial role in integrated optics. The development of passive and active devices such as splitters, waveguides, multiplexers and optical amplifiers is by now established on rigid substrates. Therefore, an important further step to improve this kind of technologies and open the route to new applications is to extend these functionalities to mechanically flexible devices. One fundamental brick to obtain this features extension is the fabrication of low loss inorganic active planar waveguides on flexible glass substrate. Here, we present the preliminary results of a novel top-down fabrication of an active SiO-HfO:Er all-glass flexible planar waveguide, via radio frequency sputtering. The waveguiding system, deposited on ultrathin flexible glass substrate, showed an attenuation coefficient lower than 0.2 dB/cm at 1.53 ?m and exhibits emission in the NIR region.

Methanol, naturally present in small quantities in the distillation of alcoholic beverages, can lead to serious health problems. When it exceeds a certain concentration, it causes blindness, organ failure, and even death if not recognized in time. Analytical techniques such as chromatography are used to detect dangerous concentrations of methanol, which are very accurate but also expensive, cumbersome, and time-consuming. Therefore, a gas sensor that is inexpensive and portable and capable of distinguishing methanol from ethanol would be very useful. Here, we present a resistive gas sensor, based on tin oxide nanowires, that works in a thermal gradient. By combining responses at various temperatures and using machine learning algorithms (PCA, SVM, LDA), the device can distinguish methanol from ethanol in a wide range of concentrations (1–100 ppm) in both dry air and under different humidity conditions (25–75% RH). The proposed sensor, which is small and inexpensive, demonstrates the ability to distinguish methanol from ethanol at different concentrations and could be developed both to detect the adulteration of alcoholic beverages and to quickly recognize methanol poisoning.

Flexible glass photonics is a cutting-edge technological and scientific research field that, thanks to a very broad spectrum of applications, has tremendously grown during the last decade and is now a strategic topic. Here, we present the results of the spectral transmittance and reflectance of a 10-layer SiO2/TiO2 1D photonic crystal deposited on a flexible polymeric substrate under different bending conditions, obtained with a home-made adjustable sample holder.