Tailored silver coated polymer pillar metasurfaces for near-infrared refractive index sensing applications

In this work, we report the design, numerical simulation, and fabrication of plasmonic metasurfaces consisting of two-dimensional array arranged polymer pillars on glass substrate coated by a thin silver layer. Silver coated polymer pillar metasurfaces with various silver thicknesses are designed and their optical characteristics analyzed with a finite-difference time-domain (FDTD) method. The designed structures for near-infrared refractive index (RI) sensing show the sensitivities and figure-of-merits (FOM) of ∼1438.3 nm/RIU and ∼71.5 RIU−1, for gaseous media, and ∼1444.0 nm/RIU and ∼59.2 RIU−1 for liquid media, respectively. By introducing and applying the fabrication processes of 3D laser direct writing combined with sputtering technique, we have demonstrated the facile implementation of the plasmonic metasurfaces working in the near-infrared region without using the precise fabrication techniques. This work will provide general guidelines and useful approaches for plasmonic metasurface device design.