Intensity Switchable and Wide-Angle Mid-Infrared Perfect Absorber with Lithography-Free Phase-Change Film of Ge2Sb2Te5

Abstract

The range of fundamental phenomena and applications achievable by metamaterials (MMs) can be significantly extended by dynamic control over the optical response. A mid-infrared tunable absorber which consists of lithography-free planar multilayered dielectric stacks and germanium antimony tellurium alloy (Ge2Sb2Te5, GST) thin film was presented and studied. The absorption spectra under amorphous and crystalline phase conditions was evaluated by the transfer matrix method (TMM). It was shown that significant tuning of absorption can be achieved by switching the phase of thin layer of GST between amorphous and crystalline states. The near unity (>90%) absorption can be significant maintained by incidence angles up to 75 under crystalline state for both transverse electric (TE) and transverse magnetic (TM) polarizations. The proposed method enhances the functionality of MMs-based absorbers and has great potential for application to filters, emitters, and sensors.

Temperature-adaptive rooftop covering with synergetic modulation of solar and thermal radiation for maximal energy saving

“… 23 , 24 , 25 , 26 , 27 , 28 , 29 Whereas, the resonator usually shows constant solar absorptance, which cannot effectively regulate the solar heat in different seasons, resulting in limited or even counter-productive overall energy savings. Besides, there are other temperature-responsive materials with thermal emissivity modulation, i.e., chalcogenide 30 , 31 , 32 , 33 and perovskite oxide. 34 , 35 , 36 , 37 , 38 Nevertheless, the former requires much higher transitional temperature (usually above 150°C) while the latter experiences wider transition temperature range (e.g., from −176°C to 100°C), hindering their application on buildings.…”