Collecting the energy of the electromagnetic fields over the infrared band based on the metastructures

Abstract

Predicated on the surface plasmon polariton, this study proposes the metastructures (MSs) constructed from copper and general dielectric films. The MSs are specifically designed to gather electromagnetic (EM) wave energy over the infrared band on the surface. Evidence illustrates that, when EM waves impinge the surface of the MSs, there is a significant surge in surface energy density, confirmed to be a staggering 2022.90 times higher than that of the ancillary EM waves. This substantial multiplication owes its genesis to the enhanced impedance matching between the MSs and free space. Furthermore, the MSs demonstrate the ability to accurately determine refractive indices ranging from 1 to 1.39, as well as measure hydrogen density spanning from 0 g/cm3 to 0.13 g/cm3. This is achieved through the assessment of absorption peak locations, the intensity of absorption, and the field enhancement factor (FEF) at the peak. The subtle absorption peak experiences a shift in alignment with the changes in refractive indices. The relationship between the peak position and the refractive index demonstrates an exceptional degree of linearity, achieving the R2 value of 1. The values of Q, Sλc, and FOM average at 1437, 1.24 μm·RIU−1, and 682.38 RIU−1, respectively. The study also examines the effects of the incident angle of the external electromagnetic (EM) field and the number of dielectric films. Within a limited range of incident angles, an increase in the angle results in a shift of the absorption peak towards shorter wavelengths. The number of films plays a role in modifying the absorption intensity and the field enhancement factor (FEF) at the peaks. The proposed MSs offer improved energy harvesting capabilities from the surface EM fields. They can also be employed for refractive index detection. Besides, the field enhancement phenomenon provides valuable insights into the adsorption and storage of the hydrogen.