Numerical study of ultra-broadband wide-angle absorber

• Published in: Results in physics 2021-05, Vol.24, p.104146, Article 104146
• Main Authors: Jiao, Shengxi, Li, Yu, Yang, Hanrui, Xu, Shibo
• Format: Article
• Language: English
• Subjects: Absorber; FDTD; Metamaterial; Plasmon resonance; Ultra-broadband
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2021.104146

•The absorber can achieve a high absorption efficiency of 94% in the 1300 nm wavelength range.•The thickness error of the absorber has a small influence on the absorption rate and is simple to manufacture.•The half-axis and structural period of the elliptical can be adjusted to control the intensity and range of the absorption spectrum.•The shape of metal nanoparticles has great influence on the absorption properties.•The absorber has the characteristics of wide angle and polarization insensitivity. This paper proposes an ultra-broadband absorber numerically demonstrated with the finite-difference-time-domain method (FDTD). The absorber is composed of a bottom layer of refractory metal tungsten (W), an intermediate dielectric layer of aluminum trioxide (Al2O3), and a top layer of refractory metal titanium (Ti) nanodisks, which are arranged periodically and symmetrically in an elliptical array. The optimization results show that the average absorptivity of the designed absorber is 94% within the wavelength range of 500 ~ 1800 nm with an absorption bandwidth at 1300 nm, which can reach 100% at 1200 nm. It was further found that the perfect absorption and broadband absorption performance is revealed by the coupling of surface plasmon resonance (SPR) and local surface plasmon resonance (LSPR) by analyzing the distribution of electromagnetic fields. The designed absorber with polarization insensitivity and wide angle characteristics is simple and easy to manufacture, which can be applied in many fields including solar absorbers, photodetectors and optical imaging.