In this paper, an ultra-broadband perfect absorber based on a four-layer pyramid metamaterial and a metal insulator metal (MIM) structure has been demonstrated and investigated. Finite-difference time-domain (FDTD) results indicate that the absorption originates from localized surface plasmons and waveguide mode resonance effect. An average absorption of 96.18 % with bandwidth ranging from 308 nm to 2387 nm was achieved, and the average absorption in the entire wave band (200–2800 nm) was approximately 94.64%. The results of the impedance matching theory are consistent with the FDTD simulation. Polarization insensitivity was investigated by studying the absorption characteristic of TE and TM polarizations. The effect of top and bottom materials was investigated and compared in detail. Moreover, by adjusting the geometrical size, the absorption performance can be fine- tuned. In addition, the proposed broadband absorber exhibited excellent absorption stability and environmental refractive index tolerance. Without noble metal materials, the proposed structure can reduce the fabrication costs. We believe that the proposed broadband absorber has potential applications in solar cells, infrared imaging, and thermal emitters.

In this paper, a polarization-insensitive and broadband absorber based on Al 2 O 3 - Ti - Al 2 O 3 rectangular periodic sandwich structure has been studied. Simulations indicate the absorbance remains over 97% at the wavelength from 599 nm to 1912 nm, and the corresponding average absorption is up to 98.5% in this range. Moreover, the broadband absorption is background refractive index and polarization insensitive. The absorption mechanism of the broad-band is studied by impedance-matching theory and finite difference time domain (FDTD) method, which is mainly originated from the cavity plasmonic resonance, surface plasmonic dipolar resonance, and near field plasmonic coupling effect. The proposed broadband absorber is expected to play a role in solar cell, which can be applied in the areas of solar cell design, imaging, and thermal emitters. Moreover, the use of Ti material and Al 2 O 3 instead of noble metals has the advantages of thermal robustness, and lower cost.

No abstract

No abstract

In this paper, a broad band absorber based on a double-ring coupled disk resonator periodic structure, which can work in the visible and mid infrared range, is proposed and investigated. Results show the absorbance is large than 92.4% in the range of 300 nm–4096 nm, and the average absorption is about 97.4% from the visible to mid-infrared bands. Besides, the proposed absorber is wide angle acceptance, background refractive index (RI), and polarization state insensitive. The absorption mechanisms are analyzed and found that it mainly originated from the dielectric lossy property in short-wavelength and gap plasmonic resonances in long-wavelength. It is believed the proposed absorber can find potential applications in the fields of solar cell devices, thermal emitters, and plasmonic imaging.