Manipulation of Spatial Infrared Emission Based on W-Doped Vanadium Oxide Films toward Thermal Coding

Active thermal radiation control of an object requires adaptive and flexible strategies to cope with emissivity engineering and its temperature dependence. On the other hand, the concept of digital coding allows a high degree of freedom in manipulating the interacting physical quantities based on local discretized features. Learning from this idea, this study put forward the manipulation of spatial infrared emission based on tungsten (W)-doped VO2 films toward thermal coding. Here, 1-bit coding worksheets created by low-emissivity, that is, code '0 & PRIME;, and high-emissivity, that is, code '1 & PRIME;, shift with materials metal-insulator phase transition to encode emissive information in the temperature domain. It is shown experimentally that this concept has marked implications on thermal radiation control at Mid-infrared, among which are as follows: digital anti-counterfeiting by in-plane spatial coding of a group of VO2 thin films with various W-doping density and infrared camouflage by out-of-plane spatial coding of them. With a W-doping gradient of 0%, 0.8%, and 1.7%, the three-phase transition points in the temperature domain, that is, 72, 63, and 45 & DEG;C, give a remarkable modulation range of 27 & DEG;C. These phenomena pave the way for new classes of emissivity engineering for more accurate, flexible, and adaptive thermal radiation control.