Femtosecond Laser Induced the Graded Impedance Matching Structure to Achieve Multi-Spectrum EM Wave Absorption Performance

Abstract

Optimal impedance matching is crucial for enhancing the performance of electromagnetic (EM) absorbing materials. In this study, a gradient impedance matching layer with component gradient and structural gradient was prepared on SiCf/SiCN composites by femtosecond laser (FS-laser) with different adjacent spot distance. The results show that the EM wave absorption is optimal when the spot distance is 30μm, possessing the minimum reflection coefficient (RCmin)of -15 dB with a thickness of 2.05mm, and the absorption performance at the frequency of 9.9GHz reaches 96.8%, while the absorption in the UV-to-NIR ranges reaches 82%. This is attributed to the appropriate adjacent spot distance which allows the FS-laser irradiated SiCf/SiCN composites surface to build nanoparticle-attached dune-like periodic structures from the structure and composition together regulating the impedance matching. In addition, FS-laser-induced defects and nano-heterogeneous interfaces enhance the polarization loss. This study provides a new technological approach to the multi-spectrum EM wave absorption properties of SiCf/SiCN composites.

Keywords: Femtosecond laser, SiCf/SiCN composites, wave absorption performance