Fabry-Perot cavity resonance based metamaterial absorber for refractive index sensor at infrared frequencies

We present numerical studies on a simple metamaterial absorber design operating at near-infrared frequencies. The absorber consists of a one-dimensional silicon strip array on a silicon substrate followed by a thin layer of gold with a thickness of 30 nm. Computer Simulation Technology Microwave Studio (CST Microwave Studio) based on finite integration technique was used for numerical simulations and to understand the mechanism of absorption in the system. Simulation results show that the absorber has an absorptance of around 0.99 with a full width at half-maximum (FWHM) of 18 nm. The absorption is caused by the simultaneous excitation of Fabry-Perot (FP) cavity resonance in the strip and between the consecutive strips, which leads to the confinement of electric fields in the strip and between the strips. In addition, we have also analyzed the sensing performance of the absorber in refractive index (RI) and found that it has high sensitivity and a large figure of merit (FOM). Therefore, the absorber can be exploited for high-performance RI sensor for sensing chemicals and biological samples, and even acidic samples due to its component's wise robustness.

Automated summary

The numerical studies show that the metamaterial absorber operating at near-infrared frequencies has high absorptance and a narrow full width at half-maximum, achieving efficient absorption. Moreover, the absorber demonstrates high sensitivity and a large figure of merit in refractive index sensing, indicating its potential for high-performance optical sensing applications.