Epsilon-near-zero (ENZ) thin films stack on a metal-based bottom layer within a dual-functional system for thermal infrared camouflage and thermal management within the atmospheric window.
Thermal infrared camouflage aims to reduce the detectability of a target using thermal imaging devices. Given the typically high thermal emissivity in everyday environments, the thermal emissivity of the background environment must be considered. The conventional low-emissivity strategy for thermal camouflage is only effective for targets at extremely high temperatures, making it unsuitable for applications near room-to-medium-high temperature range (<350 °C).
In a recent study published in Materials Horizons, Professor Hsuen-Li Chen from the Department of Materials Science and Engineering at National Taiwan University led his research team in designing an innovative multilayer thin-film structure. This structure introduces metallic glass into infrared thermal camouflage technology, exploiting its adjustable emissivity to accommodate diverse infrared thermal camouflage scenarios. Moreover, this is the first time combining metallic glass with the Berreman mode of epsilon-near-zero (ENZ) thin films.
In the long wave infrared (LWIR, 8–14 μm) regions, the small viewing angle exhibits the optical properties of metallic glasses. As the viewing angle increased, driven by the multiple Berreman modes of the ENZ thin films, it provided high thermal emissivity in transverse-magnetic (TM) polarization. It enabled thermal management without compromising the thermal camouflage performance. The cooling power exhibited by ENZ thin films on metallic glass surpassed that of the conventional low-emissivity strategy for thermal camouflage by a factor of 1.79. Furthermore, the thermal images indicated over 97% similarity in thermal radiation between the target and background environments. This presents new avenues for advancing infrared thermal camouflage technology.
Prof. Hsuen-Li Chen’s email address: [email protected]
