Constrained multi-objective optimization problem model to design multi-band terahertz metamaterial absorbers

The multi-band metamaterial absorbers studied today offer optimal sensing perfor-mance by maximizing the absorption at resonance frequencies. A constrained multi-objective optimization problem (CMOP) model is proposed to intelligently obtain the optimized geo-metrical parameters of the designed MA for optimal multi-band absorption. The proposed multi-band terahertz metamaterial absorber is formed by a patterned metallic patches (symmetric snowflake-shaped resonators) layer and a continuous metallic layer separated by a dielectric layer. The simulation results show that there are three discrete narrow resonance peaks with the absorption of 99.1%, 90.0%, and 99.9% in the range of 0.5-2 THz after being optimized by the proposed CMOP model. The reflection loss of all resonance modes is improved significantly compared with the conventional brute-force approach. Specifically, reflection loss at the highest resonance frequency is suppressed from-6.76 dB to-28.17 dB. Consequently, the reported MA design can be used as a refractive index sensor with the highest sensitivity of 495 GHz/RIU and the figure of merit (FoM) of 8.9 RIU-1 through a refractive index ranging from 1.0 to 1.6 at the analyte thickness of 18.5 mu m. It is worth noting that most of the liquid samples have a refractive index ranging from 1.0 to 1.6. Therefore, the reported sensor can be used for liquid detection with high sensitivity.

Automated summary

The study focuses on the optimal sensing performance achieved by maximizing absorption at resonance frequencies using multi-band metamaterial absorbers. A constrained multi-objective optimization problem (CMOP) model is proposed to obtain the optimal geometric parameters for multi-band absorption. The simulation results show optimization of absorption for three narrow resonance peaks in the range of 0.5-2 THz, significantly improving the reflection loss compared to conventional methods. The reported design can be used as a refractive index sensor for liquid detection with high sensitivity.