Three-Dimensional Polarization-Insensitive Perfect Absorber Using Nanorods Array for Sensing and Imaging

The analysis of a plasmon-induced transparency (PIT) effect in silver metasurface with using a square array of nanorods is numerically and analytically reported. The properties of the structure as a function of geometrical parameters, plasmonic metasurface materials, and incident angles with different polarizations are analyzed to improve the performance of the structure in terms of sensitivity and tunability. A proposed structure can operate with a high value of sensitivity of 1200nm/RIU when the changing of the sensing material refractive index is 0.2RIU, which stems from the high intensity of the electric field in nanorods array. The PIT wavelengths are not sensitive to the incident angle and its polarization, as well. Moreover, the array of nanorods has a nanoscale footprint of 200nm × 200nm × 50nm, which is proper for photonic integrated circuits. This scheme paves the way for designing nanosensor devices with perfect absorbing.