Ultra-broadband wide-angle terahertz absorber realized by a doped silicon metamaterial

Metamaterial absorber as a functional device has been extensively studied in the past decade, and its performance is continuously improved. Here we present a wide-angle terahertz absorber through polarization - insensitive doped silicon. The structural unit cell consists of a square silicon ring and a silicon substrate. Full -wave simulated results show that the designed absorber has excellent performance in the frequency range of 0.7-5.7 THz with the center frequency of 3.2 THz. The relative bandwidth ratio is 156.25% with absorptance greater than 90%. The design is insensitive to polarization at the small incident angle and still shows good performance over a wide range of incident angle. The proposed system may find potential applications in terahertz energy harvesting and thermal emission.