Self-Adaptive Multistage Infrared Radiative Thermo-Optic Modulators Based on Phase-Change Materials.

Phase-Change Materials (PCMs) are widely applied in dynamic optical modulation due to the dramatic changes in their complex refractive index caused by temperature variation. As the functionality varies, the application of a single PCM cannot meet the compact, efficient and broadband needs of optical modulators. In this work, we combine vanadium dioxide (VO₂) and a chalcogenide (Ge₂Sb₂Te₅ (GST) or In₃SbTe₂ (IST)) to obtain a VO₂–GST/IST multiple-stack film that is optimized by a genetic algorithm. This film has a wide spectrum and high modulation properties with three self-switchable modes varied by temperature, including transmission, absorption and reflection. The optimal results are an average normal transmittance, absorbance, and reflectance of 0.76, 0.91, 0.86 in 3–5 μm and 0.72, 0.90, 0.90 in 8–14 μm under different temperature ranges. The film enhances the transmission and absorption properties due to the formation of anti-reflective coating and Fabry–Perot resonance. Compared with GST, the film maintains high reflectance due to the metal-like interface reflection of crystalline IST, which exhibits metallic properties. For different polarization states, the film demonstrates great directional insensitivity when the incidence angles vary from 0° to 60°. The designed self-adaptive multistage infrared radiative thermo-optic modulator has promising implications for optical fuse, fiber-optic communication and energy storage fields. [ABSTRACT FROM AUTHOR]