Design of broadband and monolayer terahertz metasurface absorber with genetic algorithm optimization

Terahertz (THz) absorbers have drawn great attention due to their potential applications in high-resolution imaging systems, sensing, and imaging. In particular, metasurface-based THz absorbers have exhibited the exotic advantage in high efficiency and broad bandwidth benefitted from the excellent abilities of metasurface in flexible modulating electromagnetic (EM) waves. However, the interactions between metasurface and EM waves are complex, and the metasurface-based absorbers have many structural parameters to optimize for high performance. Therefore, the absorbers are constrained by the manual design process with limited geometry complexity and tedious parameters sweeping. In this paper, the genetic algorithm (GA) is employed to the design of THz metasurface absorber. The EM responses of metasurface device is calculated by a simple yet powerful analytic method derived from catenary field. The employment of GA can achieve the automatic design process and demand-oriented reverse design for high performance and decreasing time consumption. As a proof-of-concept, the broadband and monolayer metasurface terahertz absorber with absorbance exceeding 80% in the frequency range from 1 to 4 THz is designed by the proposed strategy based on five typical types of metasurface. The investigations of this article present important guidance and a promising approach to design and optimize metasurface-based devices for their practical applications.