Ultra-broadband terahertz metamaterial absorber using a simple design method

Using a simple design method cutting away some parts of a circular metallic patch resonator, we propose an ultra-broadband terahertz metamaterial absorber (MA) with bandwidth of 4.11 THz. Simulation results demonstrate that the simple design method greatly improves the absorption performance compared with previously reported absorbers. The proposed absorber exhibits the co-polarization ultra-broadband absorption performance with absorptivity above 90% in the range of 2.65–6.76 THz and the relative absorption bandwidth (RAB) of 87.35%. Moreover, the proposed absorber can maintain high absorptivity above 80% for incident angles up to 40° under both transverse electric (TE) and transverse magnetic (TM) polarizations. The ultra-broadband absorption originates from the combination of dipolar and LC resonances. The simple design method can also be applied to some other structures such as square metallic patch resonator. Furthermore, by adjusting the dimensions of proposed absorber, a broadband microwave MA can be easily obtained. Therefore, it can become an effective design method to achieve broadband absorption in various frequency ranges from microwave to optical frequencies. • A simple design method for enhancement of absorption bandwidth was presented. • This method greatly improves the absorption performance of the metamaterial absorber. • This method provides us the flexibility to choose the resonator type and working frequency range.