Design proposal for highly sensitive infrared metamaterial-based sensors

Metamaterial-based infrared sensors have attracted a lot of attention due to their ease of fabrication and various applications. In this paper, sensing capability of various metamaterial architectures, with different geometrical designs, is investigated. It turns out that some of these designs represent sensitivity values comparable to those of the best metamaterial sensors ever reported in literature. Some of these designs represent perfect absorption and some others represent electromagnetically induced reflectance (EIR). Between them, the best structure in sensing capability feature has a relatively simple architecture as well. Its unit cell contains two metallic nano-plates within which two horizontal nano-bars are emptied out. These sheets are located at the two ends of the unit cell. Moreover, a pi-shaped metallic element is also inserted between the two nano-plates. In addition to representing the interesting behavior of EIR, this structure provides a sensitivity value of 4077.2 nm/RIU. This is among the highest values reported in literature for metamaterial sensors operating in the near infrared region. The high value of sensitivity, along with the simplicity of the structure design, makes the idea of suitability of the proposed sensor for practical applications viable. Finally, effects of geometrical parameters on the sensitivity and resonance frequency of the sensors are investigated. It is found that the resonance frequency can be tuned in the range of 250-350 THz. This tunability of the resonance frequency is another promising point associated with the proposed sensors for practical applications.