Magnetic and stackable flexible photonic crystal perfect absorbers

The detrimental effects of electromagnetic pollution on wireless communication and potential health risks necessitate the development of efficient mitigation strategies. However, traditional absorbing materials and existing metamaterial absorbers face limitations in terms of cost, complexity, and tunability. In this study, we propose an improved design for a highly efficient and tunable metamaterial absorber called a photonic crystal (PhC) absorber. It involves a membrane with periodic holes in a square pattern, with carbon iron powder as the absorbent material and silicone as the matrix. Radar cross section measurements confirm the PhC absorber's performance, with maximum absorption of 53 dB and a considerably large effective bandwidth. The PhC absorber exhibits magnetic tunability, and a magnetic field shifts the maximum absorption position to higher frequencies and widens the effective bandwidth. Increasing the number of absorber layers in the stackable PhC configuration lowers the resonant frequency and widens the relative bandwidth. With its superior absorption capability, tunability, stackability, flexibility, and feasible fabrication process, the PhC absorber demonstrates considerable potential for various absorbing meta-devices.