Revelation of a tunable near infrared metamaterial and its sensing properties

All-dielectric metasurfaces based on high refractive index material are becoming important components of optoelectronic devices. However, the achived functions are often fixed by the traditional all-dielectric metasurfaces due to the resonant properties are primarily excited based on the design strategies. Optically behaviors of these metasurfaces are solidified at the manufacturing stages. It is of great significance to design and verify an alldielectric metasurface with dynamic modulation and reconfigurable properties. Here, the silicon and Ge2Sb2Te5 (GST) blocks are combined in a hybrid arrays to achieve a dynamically modulated and reconfigurable all-dielectric metasurface. Based on the amorphous state of GST, two absorption peaks are excited by this metasurface: P1 peak (amplitude 0.87, resonance wavelength 1302 nm) and P2 peak (amplitude 0.78, resonance wavelength 2008 nm). Since the GST block is in the crystalline state, only the P1 peak (the measured amplitude is 0.71 and the resonant wavelength is 1311 nm) is obtained. This all-dielectric metasurface is highly sensitive to human body fluids (glucose solution, sweat, and urine) and ambient temperature, which can be applied in health information and temperature sensors in travel or healthy care hotel, etc. Based on optimization the crystallinity of the GST block, the dynamic modulation characteristics is achieved by this all-dielectric metasurface. The measurement results show that P2 peak is insensitive to the incidence angle of electromagnetic wave. On the contrary, with the increase of incidence angle, the P1 peak is gradually divided into two new absorption peaks (regardless of whether the GST block is in amorphous state or crystalline state).