Near-perfect spectrally selective emitter for infrared stealth and radiative cooling

In modern military applications, the advancement of infrared detection technology has posed significant challenges to the concealment of military targets. Traditional infrared stealth technologies struggle to balance low emissivity and heat dissipation requirements, limiting their effectiveness. In this study, we design a near-perfect spectrally selective emitter based on a combination of Si/HfO2 multilayer films and SiO2. By optimizing the structural parameters using the transfer-matrix method, this emitter achieves average emissivities as low as 0.06 and 0.11 in the 3–5 and 8–14 μm atmospheric windows, respectively, effectively suppressing infrared radiation and meeting the low emissivity requirements for infrared stealth. In the 5–8 μm non-atmospheric window, the average emissivity reaches 0.84, demonstrating excellent radiative cooling performance. The figure of merit of 0.88 highlights its near-perfect infrared spectral modulation capability. Through simulations of electric field distributions and power loss density, the physical mechanisms behind the selective emissivity are clearly elucidated. Additionally, the effects of layer thickness, light polarization, and incident angles on emissivity are analyzed, revealing stable performance within an incident angle range of 0°–40°. Infrared thermal imaging simulations and related performance calculations confirm that the radiative temperature is significantly lower than the surface temperature, effectively reducing the temperature difference between the target and the background. This ensures strong radiative cooling capabilities while minimizing the target's infrared signature. Compared to previous research, the emitter in this study exhibits superior performance, offering a more efficient and feasible solution for infrared stealth and spectral modulation, with broad application prospects in fields such as infrared stealth and thermal management.