A Dual Band THz Metamaterial based Absorber for Gas Refractive Index Sensing

This research work aims to design dual band terahertz metamaterial based absorber for sensing the refractive index of gases like carbon dioxide, helium, hydrogen etc. This proposed design is based on combined hexagonal rings resonators on Gallium Arsenide substrate which attains a very high absorption rate of 99.068% and 97.41% at 3.3175 THz and 3.5787 THz respectively. Q-factor and Figure of Merit (FoM) was found to be 151.69 and 51.288 respectively at 3.3175 THz which is quiet high and suitable for sensing applications and thus makes refractive index sensor. The refractive index was varied from n=1 to 1.1 as the refractive index of some gasses falls between this range and the sensitivity was found to be 1.121 THz/RIU. Parametric analysis was also done to chose the optimum value of all the geometric parameters of the proposed design. The absorption mechanism was also deeply studied by current distribution plot. This proposed absorber is suitable for sensing the harmful and toxic gases.