Metamaterial absorber with broadband and superior absorption realized by optical nanotrapping hybrid cavity

In this paper, we present the design of a solar absorber that efficiently integrates the properties of perfect absorption, ultra-broadband characteristics, polarization independence, and insensitivity to large incident angle within a straightforward metamaterial absorber structure. Our proposed absorber consists of a four-layer nanodisk array composed of titanium and silicon nitride. The patterned titanium layer forms hybrid cavity that induces the coupling of multiple resonance modes. Simulation results demonstrate that the proposed absorber attains an average absorption efficiency of 98.19 % within the wavelength range of 280 nm to 2500 nm, and it also achieves an efficient absorption of 94.71 % under the air mass 1.5 solar spectrum. Furthermore, the absorber exhibits excellent insensitivity in both transverse magnetic and transverse electric polarizations, angle insensitivity to incident electromagnetic waves, and a high tolerance for manufacturing errors. These qualities make it well-suited for practical applications, including solar energy harvesting, infrared imaging and spectroscopy, and optoelectronic devices.