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Applying coatings that suppress the radiance changes related to temperature-dependent blackbody emission enables temperature-independent optical and sensing systems. Phase-change materials can significantly modify their optical properties within their transition window, but compensating for the large mid-wave infrared (MWIR, 3–5 µm) variation is demanding: blackbody radiance at 3 µm increases nearly 10-fold as the temperature rises from 30 °C to 80 °C. Vanadium dioxide VO2, whose insulator–metal transition offers a sharp contrast and a low-loss insulating state, is attractive for applications in thermal management, but simple thin-film designs cannot provide full compensation. We demonstrate metasurface coatings that provide this compensation by constructing an array of metal–VO2–metal antennas tuned to maintain constant thermal emission at a target wavelength over a temperature range of 30 °C to 80 °C. Antennas of several lateral sizes are combined, so their individual resonances collectively track the Planck change. This design provides both optical contrast and the correct temperature derivative, which are unattainable with homogeneous layers. Our approach results in a negligible apparent temperature change of the metasurface across the 30–80 °C range, effectively masking thermal signatures from MWIR detectors stemming from the low losses of VO2.
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Temperature-Independent Thermal Radiation Design Using Phase-Change Materials
The ability to treat the surface of an object with coatings that counteract the change in radiance resulting from the object’s blackbody emission can be very useful for applications requiring temperature-independent radiance behavior. Such a response is difficult to achieve with most materials except when using phase-change materials, which can undergo a drastic change in their optical response, nullifying the changes in blackbody radiation across a narrow range of temperatures. We report on the theoretical design, giving the possibility of extending the temperature range for temperature-independent radiance coatings by utilizing multiple layers, each comprising a different phase-change material. These designed multilayer coatings are based on thin films of samarium nickelate, vanadium dioxide, and doped vanadium oxide and cover temperatures ranging from room temperature to up to 140 °C. The coatings are numerically engineered in terms of layer thickness and doping, with each successive layer comprising a phase-change material with progressively higher transition temperatures than those below. Our calculations demonstrate that the optimized thin film multilayers exhibit a negligible change in the apparent temperature of the engineered surface. These engineered multilayer films can be used to mask an object’s thermal radiation emission against thermal imaging systems.
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- Award ID(s):
- 2418519
- PAR ID:
- 10577865
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Coatings
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2079-6412
- Page Range / eLocation ID:
- 38
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/coatings15010038
