Tailored materials efficiently absorbing electromagnetic radiation across increasingly broad frequency ranges are needed for applications such as stealth or energy harvesting. To design them, one may combine approaches that have already led to efficient absorbers, with the aim of reaching record absorption amplitudes and spectral widths. This includes: assembling structures resonating at different frequencies, using lossy compounds to broaden the resonances, roughening or folding surfaces to better trap radiation, among other possibilities. However, many combinations lead to an unsatisfactory absorption amplitude or width, making the search for specific configurations necessary. In this context, researchers harness computer-aided-design and Maxwell solvers to test virtually the absorption properties of potentially suitable materials, and propose adequate configurations for fabrication. Following this approach, Junqi Yao and coworkers have found a material prone to enabling a strong absorption in a remarkably broad THz frequency range. It consists of resonant microscale domes made of vanadium dioxide and gold deposited on a substrate. Upon folding the substrate to form U-shaped cavities, the spectral width in which absorption overcomes 90% at normal incidence is multiplied by 4, to span from 0.6 to 6 THz. This performance is attributed to the suitable combination of dielectric losses, magnetic and cavity resonances. A remarkable stability of absorption versus the polarization and angle of incidence of radiation is also reported.

---

---

 Add Comment

You must log in to add comments.