All-metal frequency-selective absorber/emitter for laser stealth and infrared stealth

In this paper, an all-metal nanostructure is designed with a large frequency ratio (similar to 6) and a large bandwidth ratio (similar to 32), and consists of period slit-box cavities and nanodisk clusters. It is a nearly perfect absorber at 1.064 mu m to achieve laser stealth, a frequency-selective emitter with low emissivity in wavelength ranges 3-5 and 8-14 mu m to achieve infrared stealth, and also an emitter with near unity emissivity at 2.709 mu m and 6.107 mu m to compensate for the decrease of radiation heat transfer owing to the low emissivity. The absorption/emission peaks are all the Lorentzian shape, and the bandwidths, defined as full width at half-maximum, are 35, 408, and 1124 nm at 1.064, 2.709, and 6.107 mu m, respectively. The electric and magnetic field distribution shows that the slit behaves like a capacitor, the box behaves like an inductance, and the nanodisk clusters can excite electric dipole resonance. Considering the solar irradiation, the nanostructure maintains middle-wavelength infrared signal reduction rates greater than 80% from 450 to 1000 K, and long-wavelength infrared signal reduction rates greater than 90% from room temperature to 1000 K. The laser and infrared stealth performances of our nanostructure at 473 K are also studied with different incident angles and polarization angles. (C) 2018 Optical Society of America