Ultrabroadband Directional Tunable Thermal Emission Control Based on Vanadium Dioxide Photonic Structures

The manipulation of thermal radiation amplitude or direction over a broadband spectrum is a fundamental capability, demonstrating significant potential in thermal management and infrared information encryption. However, existing approaches cannot control both aspects simultaneously. In this study, an ultrabroadband directional tunable thermal emitter (UDTTE) utilizing the metal-insulator transition properties of vanadium dioxide photonic structure and the Brewster effect is proposed. Before the phase transition, the UDTTE exhibits an average emissivity as low as 0.07 across the 3-20 µm band and the entire range of angles. After the phase transition, the UDTTE maintains a low emissivity of 0.33 for incident angles below 73° but displays a high emissivity of 0.78 in the 73°-83° range. This designed experiments in information encryption demonstrate that the UDTTE can synergistically utilize temperature, viewing angle, and polarization to achieve multi-level encryption of IR information. This strategy further enhances the capability to manipulate thermal radiation and holds promise for advancing technologies in information security, IR camouflage, and thermal management.