Jang Eunbi, Cho Junghee, Kang Chanik, Chung Haejun
Department of Artificial Intelligence Semiconductor Engineering, Hanyang University, Seoul 04763, Republic of Korea.
Department of Electronic Engineering, Hanyang University, Seoul 04763, Republic of Korea.
Nanomaterials (Basel). 2025 Jul 1;15(13):1024. doi: 10.3390/nano15131024.
Electromagnetic absorbers combining ultrathin profiles with robust absorptivity across wide incidence angles are essential for applications such as stealth applications, wireless communications, and quantum computing. Traditional designs, including Salisbury screens, typically require thicknesses of at least a quarter-wavelength (λ/4), restricting their use in compact systems. While metamaterial absorbers (MMAs) offer reduced thicknesses, their absorptivity generally decreases under oblique incidence conditions. Here, we introduce an adjoint optimization-based inverse design method that merges the ultrathin advantage of MMAs with the angle-insensitive characteristics of Salisbury screens. By leveraging the computational efficiency of the adjoint method, we systematically optimize absorber structures as thin as λ/20. The optimized structures achieve absorption exceeding 90% at the target frequency (7.5 GHz) and demonstrate robust performance under oblique incidence, maintaining over 90% absorption up to 50°, approximately 80% at 60°, and around 70% at 70°. Comparative analysis against particle swarm optimization further highlights the superior efficiency of the adjoint method, reducing the computational effort by approximately 98%. This inverse design framework thus provides substantial improvements in both the performance and computational cost, offering a promising solution for advanced electromagnetic absorber design.
将超薄外形与宽入射角下的强大吸收率相结合的电磁吸收器对于隐身应用、无线通信和量子计算等应用至关重要。包括 Salisbury 屏在内的传统设计通常需要至少四分之一波长（λ/4）的厚度，这限制了它们在紧凑型系统中的应用。虽然超材料吸收器（MMA）的厚度有所减小，但其吸收率在斜入射条件下通常会降低。在此，我们引入一种基于伴随优化的逆向设计方法，该方法将 MMA 的超薄优势与 Salisbury 屏的角度不敏感特性相结合。通过利用伴随方法的计算效率，我们系统地优化了厚度仅为 λ/20 的吸收器结构。优化后的结构在目标频率（7.5 GHz）下实现了超过 90% 的吸收率，并在斜入射下表现出强大的性能，在 50° 时保持超过 90% 的吸收率，在 60° 时约为 80%，在 70° 时约为 70%。与粒子群优化的对比分析进一步凸显了伴随方法的卓越效率，将计算量减少了约 98%。因此，这种逆向设计框架在性能和计算成本方面都有显著提升，为先进电磁吸收器设计提供了一个有前景的解决方案。
