Design and Simulation of a polarization insensitive Terahertz Metamaterial Absorber for Enhanced Refractive Index Sensing

This study introduces a novel metamaterial absorber (MMA) for refractive index sensing, utilizing a unit cell structure composed of a resonator and ground plane made of gold and a PTFE substrate. The proposed MMA exhibits exceptional absorption performance, with four distinct resonant peaks at 5.23, 5.82, 6.25, and 6.58 THz, achieving near unity absorption of 90.6%, 99.90%, 88.74% and 99.7% respectively. Utilizing Finite Integration Technique (FIT), impedance matching was analyzed, polarization dependency, and angular stability of the MMA. Polarization Conversion Ration being zero ensures the structure being an absorber and not a polarizer. The MMA achieves quality factors of 243.06, 208, 114.3 and 102.97. Sensitivities of 0.68, 0.61, 0.83, and 0.91 THz/RIU and FOM of 31.62, 21.78, 15.17, 14.24 was found for the respective resonance frequencies. This demonstration of high sensitivity to refractive index changes, makes it suitable for applications such as fuel adulteration detection and cancerous cell identification.