The electromagnetic interference (EMI) shielding window is of great significance for precision aeronautic, medical, civilian, and research facilities, which require it also needs good optical transmittance while maintaining strong EMI shielding performance.

Current high-performance EMI shielding windows predominantly adopt transparent conductive materials for reflecting incident microwaves, generating strong background scattering signals to cause secondary EM pollution in the space to complicate the electromagnetic environment. Although some transparent metamaterial absorbers have been developed and exhibit excellent absorption performance, it is still confined to the visible region. There are many challenges in the near-infrared region.

The research team led by the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, has proposed and demonstrated a high-performance broadband EMI shielding window based on a metamaterial absorber. The result, entitled “High-performance broadband electromagnetic interference shielding optical window based on a metamaterial absorber,” was published in Optics Express [2020, 28(18): 26836-26849].

An optically transparent metamaterial EMI shielding window with broadband absorption was proposed theoretically and verified experimentally. The experimental measurements showed that the window achieves strong absorptivity, > 90%, covering an ultrawide frequency range of 7.8–18.0 GHz, and the measured shielding effectiveness (SE) of the window was > 18.25 dB, at 7.0–18.0 GHz, which agreed well with the simulated results. Moreover, the absorption mechanism was revealed by establishing an equivalent circuit model and studying the distributions of the electric field and surface current of the structure.

Surprisingly, the researchers found that the measured average optical transmittance was fixed at ~73.10% in the visible–near-infrared (Vis–NIR) region of 400–1,500 nm. Besides, the specific design also makes the designed device polarization-independent and insensitive to the incident angle for both TE and TM mode waves. These excellent properties are promising for use in high-performance low-reflection transparent EMI shielding materials, which are highly desirable for modern optoelectronic systems.

This work was supported by the National Natural Science Foundation of China (NSFC) (61675219, 61875256). Hongxing Dong acknowledges the Youth Top-notch Talent Support Program in Shanghai, Shanghai Rising-star Program, High-level talents Program (2019CT001), Strategic Priority Research Program of the Chinese Academy of Sciences (XDB16030700).

Schematic diagram of the MMA-based optical window. (Image by SIOM)

Article website:
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-18-26836

Contact:
Mr. Wu Xiufeng
General Administrative Office
Shanghai Institute of Optics and Fine Mechanics, CAS
Email: xfwu@siom.ac.cn