Passive thermal radiation control based on thermochromic W-doped VO2 metasurfaces

Radiative cooling becomes a popular research topic targeting an energy efficient solution for thermal management. Vanadium dioxide (VO2), as a thermochromic material, is able to switch optical property between dielectric and metallic states depending on its temperature. We present a passive thermal management solution through a VO2 based metasurface. Through a novel ALD process, the fabricated VO2 metasurface on polyimide substratehas a room-temperature transition and a high infrared emissivity of ~0.4

Metal oxide meta-optical solar reflectors for space applications

Optical solar reflectors (OSRs) play a crucial role in the spacecraft thermal management. We present novel OSRs based on planar or non-planar metal oxide metasurface. Fabricated meta-OSRs are shown to give superior emittance performance

A novel selective carrier modulation technique to form a planar metal oxide metasurface

Metasurface devices are conventionally fabricated by physically patterning the functional film. We demonstrated a novel fabrication technique to selectively modulate Al-doped ZnO carrier concentration of planar film and form a planar optical metasurface

Smart meta-optical solar reflectors based on vanadium dioxide

Optical solar reflectors (OSRs) play a crucial role in the thermal control of a spacecraft. We present novel ’smart’ metasurface-based OSRs using vanadium dioxide (VO2), which has its infrared emittance modulated by temperature. We have investigated the infrared property of the ALD VO2 films under different anneal conditions and found the anneal condition can optimize VO2 infrared response. We have demonstrated that a superior emittance tunability and lower solar absorption for meta-OSRs than the planar film device

Novel Metal Oxide Metasurface-based Optical Solar Reflectors

Optical Solar Reflectors (OSRs) play a crucial role in thermal management of spacecraft as the outer-surface to the space environment. To achieve the thermal control, an ideal OSR should be able to reflect all the UV/Vis/NIR spectrum radiation to avoid heating up by the son and also emit blackbody radiation in infrared (IR) spectrum for thermal dissipation. Conventionally, OSRs are made of aluminium plated quartz tiles and therefore have serious issues for their heavy weight and fragile format, significantly adding the launch and assembly cost, respectively. Recently, we have proposed a meta-OSR solution based on thin film technology using Al-doped ZnO (AZO) [1] and the meta-OSRs can be fabricated on flexible substrates, making them light in weight and easy for surface mounting. In addition, we have also proposed a smart meta-OSR solution based on VO 2 , which has a tunable emissivity depending on the operational temperature [2]. In this work, we report a novel meta-OSR with a planar AZO metasurface unlike island-like metasurfaces formed by etch. The planar metasurface is fabricated through our patented plasma patterning technique [3] [4] , which can locally modulate carrier density in AZO