Research on realizing high permeability and laser stealth compatibility in visible light band with dielectric/metal/dielectric film system

Abstract

The “cat’s eye effect” in the optical window of all kinds of photoelectric equipment is the main basis of a laser active detection system, which poses a great threat to military equipment and combatants. However, under the condition of ensuring high visible transmittance, the sniper stealth scheme for anti-laser active detection remains to be discussed. In this paper, genetic algorithm is used to inverse design the metasurface anti-reflection film. The three-layer anti-reflection film are composed of Si₃N₄ and Ag , and rectangular array of metal micro-nano structures is added on the top layer to form a wavelength selective absorber, so as to achieve the effect of low reflection and high absorption at laser wavelength. By combining the device design with genetic algorithm, the parameter combination that best possesses the target performance of the device is obtained. The average transmittance in a wavelength range of 380–780 nm is 88%, and a maximum transmittance peak is 94%. The reflectance and the absorption rate at 1550 nm are achieved to be 10% and 80%, respectively. In order to better meet the requirements for practical application, we further design the cross metal array to obtain polarization insensitive characteristics. The metasurface anti-reflective membrane with improved structure can achieve an average visible transmittance of 82% and a reflectance of 5% at 1550 nm. The two metasurface anti-reflection films designed in this work do not require additional devices, and the imaging quality can be guaranteed. At the same time, it can effectively reduce the laser echo energy, so as to achieve the effect of high-quality visible light transmittance and laser stealth compatibility.