Refractive index sensor with dual sensing bands based on array of Jerusalem cross cavities to detect the hemoglobin concentrations

A metallic perfect electromagnetic absorber consisting of two-dimensional arrays of Jerusalem cross cavities placed on a dielectric substrate ended with a conducting layer acting as a back reflector is presented in this paper. The designed absorber shows more than 90% absorption around the center frequencies of 1.3-1.67 THz with quality factors of Q = 46.5 and Q = 119, respectively. The presented structure can be employed as a sensor to detect the refractive index of different materials with a sensitivity of 0.473-0.1 THz per refractive index unit (THz/RIU) and Figure of Merit, 16.9 (1/RIU) and 7.1 (1/RIU), respectively. In addition, the results show that the sensor can detect the hemoglobin concentrations with a refractive index ranging from 1.34 to 1.43 with an average sensitivity of 0.525 (THz/RIU). The designed structure has potential applications to identify other biomedical properties as well.