Directional energy weapons such as high-power microwaves and high-energy lasers pose a huge threat to optoelectronic detection systems. With that in mind, we designed an infrared optical window that has a nonlinear optical response to high-energy lasers and electromagnetic shielding to microwaves. By constructing a periodic metal circular hole array structure at the subwavelength scale, surface plasmons resonance is excited and its local field enhanced characteristics are utilized to form information transmission compatibility in the infrared band. At the same time, after laser etching off the subwavelength structure, the remaining metal forms a continuous conductive structure, forming an ultra-wideband shielding layer to achieve ultra-high and wide protection in the microwave band. Moreover, a layer of Ge₂Sb₂Te₅ thin film was deposited between the transparent substrate and the metal film. Utilizing its nonlinear optical properties of high-temperature phase transition to reduce damage of directed energy weapons to the photoelectric detection system and equipment. Thus, when the photoelectric detection system or device is damaged or interfered by signals of different frequency bands or energies, the filtering window can achieve multi-mode shielding function.

Metal mesh films have been shown to be a promising strategy to effectively mitigate the growing issue of electromagnetic interference (EMI) in optoelectronic systems. To achieve superior shielding effectiveness, it is common to increase the thickness of the mesh film. However, mesh-based shielding materials have frequency-dependent shielding effectiveness that decreases as the frequency increases. Simply increasing the thickness of the mesh cannot effectively enhance the EMI shielding effectiveness at high frequencies. This will further lead to challenges such as increased processing difficulties and higher costs. In this paper, we present an infrared transparent electromagnetic shielding window based on metal mesh with irregular patterns and proper thickness. The mesh coating is fabricated on a sapphire substrate using ultraviolet photolithography technology and exhibits an efficient electromagnetic shielding effectiveness of more than 20 dB over the wide frequency range of 1.7–18 GHz while maintaining high infrared optical transparency. More importantly, there is no distinct variation in shielding effectiveness between low and high frequency ranges, demonstrating a balanced shielding characteristic across a broad frequency band. This work could be crucial in designing cost-effective and efficient EMI shielding windows for optoelectronic systems.

The generation of a strong electromagnetic weapon requires the electromagnetic protection performance of the photoelectric system, including the high shielding and ultra-wideband protection characteristics against strong electromagnetic attacks and superhigh infrared transmittance. This article aims to excite surface plasmons by etching a subwavelength circular structure array run through a metal film. At the same time, the local field enhancement effect based on surface plasmons is used to tune specific wavelengths of light, achieving the goal of enhancing the optical transmission effect. Ulteriorly, the amplitude and position of the infrared response peak are controlled by optimizing the structural geometric parameters to achieve filtering effects in different wavebands. Furthermore, through the inversion calculation of the transmission spectrum of the circle array structure in the visible light band, the different colors of its surface under different parameters can correspond one-to-one to its performance, so as to intuitively identify different filter types and their performance. Meanwhile, the remaining metal film after etching off the circle array structure region constitutes an ultra-wideband shielding layer as a continuous conductor, achieving a shielding efficiency of more than 45 dB in the radar band (1–18 GHz). It is worth noting that the cascaded theory combines ultra-thin metal films with thick substrates to solve the problem of software running for long periods of time and under high loads during the simulation of light propagation. This scheme greatly reduces the error between simulation and practical application.

The infrared band is one of the important communication windows. Most of the detectors and sensors working in this band are designed and manufactured based on micro- and nano-lithography technology. In this article, we cut the giant-sized thickness of the transparent substrate and the metal film was uniformly sliced. Then, we used the CST software to simulate the sliced substrate and the metal film to obtain the optical response parameters for each slice. Finally, the combination of metal film and substrate was realized by cascading calculation of the two port transmission line theory, which solves problems such as overlong simulation time and cumbersome running load caused by huge grid divisions due to the difference between the substrate thickness and the response wavelength in the process of simulating light propagation. On the other hand, the cascade analysis method was experimentally verified by constructing a surface plasmon filter in the medium infrared band, which provides an effective idea and solution for bridging the gap between simulation and engineering application.