Tri-Band Plasmonic Perfect Absorber for Secure Optical Communication and Laser/Ir Signal Suppression in Defense Applications

Military camouflage and stealth technologies are vital for secure communication and defense systems. Target tracking and guidance systems monitor electromagnetic waves reflected or emitted from target or communication platform surfaces. Blocking these waves reduces platform visibility and detectability, enhancing communication confidentiality and protection against attack systems. A Metal–Insulator–Metal (MIM) structure offers electromagnetic signature reduction against laser and thermal sensors. The proposed MIM structure consists of a plasmonic nanoantenna array supporting three resonance modes to absorb electromagnetic waves at near-perfect levels. Optical tracking and free-space optical (FSO) communication systems often operate at 1.55 μm. Our designed MIM structure achieves an absorption level of 96.5% at 1.55 μm over a very narrow bandwidth, minimizing the signal returned at the FSO carrier wavelength and thereby reducing the reflected optical signature. Additionally, it provides infrared (IR) signal suppression within this spectral region. It also achieves absorption rates of 98.8% and 98.6% at 2 μm and 6 μm, respectively, supporting infrared signature suppression in these regions. Compared to similar studies, the proposed device achieves perfect absorption in three bands and demonstrates electromagnetic signature control and concealment against laser and IR detection systems, supporting its use in secure free-space optical communication and stealth-oriented defense platforms.