A 0.85 μm Optical Filter Based on the Surface Plasmon Resonance Using Four Plates of the Gold

In this paper, we propose a relatively simple circular PCF grating with four gold plates, which has high-loss filtering capabilities in the 0.85 μm wavelength range. The PCF based on four gold plates and circular air-hole grating is capable of generating electromagnetic waves propagating along the interface between the metal and dielectric medium, which can affect the light propagation characteristics of the PCF. In addition, the effects of several structural parameters including gold plate spacing (p), width (w) and height (h) of the gold plate on the filtering efficiency of the structure are examined in detail. The optimum values for the filter were found to be <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${\mathrm{p}}{=2.5}\ {\mu \mathrm{m}},\mathrm{h}{=400}$</tex> nm and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{w}{=80}$</tex> nm at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${\lambda} \text{SPP}{=0.85}\ {\mu \mathrm{m}}$</tex>. The filter performance characteristics have been analysed by means of mathematical modelling based on the finite element method (FEM).