General three-dimensional thermal illusion metamaterials

Thermal illusion aims to create fake thermal signals or hide the thermal target from the background thermal field to mislead infrared observers,and illusion thermotics was proposed to regulate heat flux with artificially structured metamaterials for thermal illusion.Most theoretical and experimental works on illusion thermotics focus on two-dimensional materials,while heat transfer in real three-dimensional(3D)objects remains elusive,so the general 3D illusion thermotics is urgently demanded.In this study,we propose a general method to design 3D thermal illusion metamaterials with varying illusions at different sizes and positions.To validate the generality of the 3D method for thermal illusion metamaterials,we realize thermal functionalities of thermal shifting,splitting,trapping,amplifying and compressing.In addition,we propose a special way to simplify the design method under the condition that the size of illusion target is equal to the size of original heat source.The 3D thermal illusion metamaterial paves a general way for illusion thermotics and triggers the exploration of illusion metamaterials for more functionalities and applications.

Two-dimensional thermal illusion device with arbitrary shape based on complementary media

On the basis of transformation thermodynamics and compensation medium theory, we develop a method to design a two-dimensional thermal illusion device with arbitrary shape, and the general expression of thermal conductivity in the each region is obtained. Simulation results show that when an object is covered with the thermal illusion device, it will accurately perform the same temperature distribution signature as another object we have predetermined. Owing to the property of deceiving and interfering with the observer, the thermal illusion device can achieve generalized thermal stealth by using thermal metamaterials, which may have a potential application in military field.

Selective thermal emission and infrared camouflage based on layered media

Infrared camouflage based on artificial thermal metasurfaces has recently attracted significant attention.By eliminating thermal radiation differences between the object and the background,it is possible to hide a given object from infrared detection.Infrared camouflage is an important element that increases the survivability of aircraft and missiles,by reducing target susceptibility to infrared guided threats.Herein,a simple and practicable design is theoretically presented based on a multilayer film for infrared stealth,with distinctive advantages of scalability,flexible fabrication,and structural simplicity.The multilayer medium consists of silicon substrate,carbon layer and zinc sulfide film,the optical properties of which are determined by transfer matrix method.By locally changing the thickness of the coating film,the spatial tunability and continuity in thermal emission are demonstrated.A continuous change of emissive power is further obtained and consequently implemented to achieve thermal camouflage functionality.In addition,other functionalities,like thermal illusion and thermal coding,are demonstrated by thickness-engineered multilayer films.