We demonstrate a dual-band, polarization-insensitive, ultrathin and flexible metamaterial absorber (MA), based on high-order magnetic resonance. By exploiting a flexible polyimide substrate, the thickness of MA came to be 1/148 of the working wavelength. The absorption performance of the proposed structure was investigated for both planar and bending models. In the case of the planar model, a single peak was achieved at a frequency of 4.3 GHz, with an absorption of 98%. Furthermore, additional high-order absorption peaks were obtained by the bending structure on a cylindrical surface, while the fundamental peak with a high absorption was maintained well. Our work might be useful for the realization and the development of future devices, such as emitters, detectors, sensors, and energy converters.

We demonstrated a multi-band plasmonic metamaterial absorber (MA), based on the near-field coupled resonators. In addition to the individual resonances of resonators in the proposed structure, which were split-ring resonator (SRR) and cross-shape structures, another resonance was also excited owing to the coupling of resonators, revealing a triple-band absorption. Furthermore, to control the absorption behavior, on the top of the SRRs, the identical SRRs made of graphene ink were pasted. By increasing the resistance of graphene ink, the coupling strength was weakened, changing the triple-band absorption to a dual-band one. Our work might be useful as the controllable devices, based on graphene-integrated plasmonic MA, such as filters, detectors and energy harvesters.

In this work, we demonstrated a tunable metamaterial perfect absorber (MPA) with broadband absorption by tuning the different states of flexible sandwiched structures (graphene conductive ink/rubber/metallic layers). The broadband absorption spectrum was tuned mechanically by changing the concave-up/down states of flexible hemispherical unit-cells. When the unit-cell was concave-up, our proposed MPAs played as a broadband absorber with a fractal bandwidth (FBW) of 107% (since an absorption over 90% ranges from 5.28 to 17.6 GHz) at the normal incidence; at the same time, this broadband absorption feature could remain well at large incident angles up to 40 deg. and regardless of polarization of the incoming electromagnetic waves. In the case of the concave-down state, a narrow FBW of only 6.8% was noticed. These results could promote great application potential, such as regarding advanced stealth devices, advances in the biomedical and the communication fields, and more.

This work proposes a facile wide incident angle metamaterial absorber (MA) using a multilayer structure. The suggested MA consists of two ring-shaped resonant layers. Under normal incidence, the proposed MPA exhibits an absorption peak at 4.31 GHz with an absorption of 98.9%. The impact of incident angle on absorption characteristics of our MA is investigated experimentally for both transverse electric (TE) and transverse magnetic (TM) modes. In the TE mode, at an incident angle of 70 degrees, the MPA exhibits two absorption peaks at 4.23 and 4.39 GHz with absorptions of 88.7% and 97.5%, respectively. In the TM mode, the absorption intensity of the proposed MA is maintained at 90% with an incident angle of up to 50 degrees and descended to below 90% at an incident angle of 70 degrees. In addition, the role of multilayer structure on the incident angle broadening of MA is also discussed and clarified.