The improvement of figure of merit with infrared perfect absorber for plasmonic resonance sensing

We present an infrared perfect absorber which combines gold nanobars and a photonic microcavity. By adjusting the structural geometry, this device is utilized for refractive index sensing. For proper designed structural parameters, it can yield more than 99% absorbance in the near-infrared frequency regime. Our work directly investigate the effect of geometry on sensing performance and it can sever as a model of coupling between localized surface plasmon within nanoparticles and propagating surface plasmon along planar metal layer for sensing applications with a perfect absorber.