Long-wavelength infrared selective emitter for thermal infrared camouflage under a hot environment

Abstract

Thermal infrared camouflage as a kind of counter-surveillance technique has attracted much attention owing to the rapid development of infrared surveillance technology. Various artificial optical structures have been developed for infrared camouflage applications under cold ambient environment (low thermal radiation), but the realization of infrared camouflage under a hot environment (high thermal radiation) is also highly desirable and has been rarely reported. Here, a lithography-free, ultra-thin, high performance long-wavelength infrared (LWIR) selective emitter for thermal infrared camouflage in a high radiation environment is proposed and experimentally demonstrated. Experimental results show that our designed selective emitter exhibits average emissivity higher than 90% over the LWIR range from 8 to 14 µm and low emissivity less than 35% outside this window. Numerical simulations were performed to optimize the geometrical structures and reveal that such a selective emission effect is attributed to the combination of multiple hybrid plasmonic resonances. LWIR thermal images show that the selective emitter can perfectly blend into the high radiation backgrounds. Furthermore, it is found that the sample displays angle-independent emission properties, indicating that our emitter offers great potential for application in evading large-angle detection.

Ultra-thin midwavelength infrared absorber using bismuth based planar thin film metamaterials

“…A large portion of electromagnetic radiation in this band can transmit directly through the Earth's atmosphere without any distortion or absorption. 1) In this context, great efforts have been made to develop perfect absorbers operating in the MWIR regime, which could inspire a vast variety of potential applications including thermal photovoltaics, 2) thermal bolometers, 3) infrared sensing, 4) infrared camouflage, 5,6) infrared photodetector, 7) radiative cooling, 8) and thermal emitters, 9,10) etc. For these purposes, many nanostructured optical systems were developed in various sizes, shapes and architectures to attain perfect absorbers, [11][12][13][14][15][16][17][18][19][20] such as plasmonic metasurfaces, optical cavities, metallic gratings and photonic crystals.…”

Dynamic modulation of thermal emission -- a Tutorial

“…Thermophotovoltaics, moreover, can be used with sources other than the sun, for example to recycle the heat generated in industrial processes. Other applications of thermal radiation, aside from energy production and conversion schemes are thermal imaging 14,15 , radiative cooling [16][17][18][19][20][21][22][23][24][25][26][27][28][29] , thermal circuitry [30][31][32][33][34][35][36][37][38][39] and camouflaging [40][41][42][43][44] , among others. Thermal radiation is traditionally assumed to be incoherent, however recent results have proven that it can possess a high degree of both spatial and temporal coherence, as we will discuss later.…”