Multi-peak narrow-band metamaterial absorber for visible to near-infrared wavelengths

This study developed a multiband metamaterial-absorbing device based on an array of gold nano-crosses for visible to near-infrared wavelengths. The proposed absorbing device is deposited on a silicon substrate and uses a metal-insulator-metal (MIM) classical structure. Numerical analyses were performed using the finite difference time domain (FDTD) method. The underlying physical mechanisms were analyzed on the basis of the structural parameters affecting the surface plasmon resonance field in the nanoarray structure. The calculations show that the proposed absorber achieves a five-band absorption in the visible to near-infrared region (700-3000 nm). After parameter adjustment and optimization, there were three absorption peaks with absorption of 99% or more and an average absorption value of 96.4% for the five peaks. Moreover, the array can be used as a biosensor to identify certain viruses, demonstrating its utility in label-free clinical sensing. In addition, the absorber is po- larization-and incident-angle-insensitive. Therefore, this device exhibits considerable potential for designing ideal absorbers and nanosensors.