The effect of metal rods in a hybrid plasmonic-photonic crystal cavity design

In this paper, a hybrid plasmonic-photonic crystal (P-PhC) structure, in which four metal rods are embedded in the resonant cavity of rod-type Si PhC structure is designed. The finite-difference time-domain (FDTD) method and finite element method (FEM) are used to evaluate the properties of the proposed hybrid structure. The obtained results show that by the cooperative coupling between the plasmonic mode induced by the metal rods and resonant PhC cavity modes, a hybrid P-PhC mode is created. The hybrid mode can be strongly confined within the cavity with a 121% reduction in mode volume compared to purely PhC, resulting in increasing the sensitivity of the proposed hybrid structure as a refractive index sensor with the sensitivity value of 1240 nm/RIU. In the proposed structure, the plasmonic field enhancement within the PhC cavity and good quality factor of 487 opens new ideas for the control of light-matter interaction in wide applications in integrated Opto-plasmonic devices for nanolasers or as sensing elements in the near-infrared spectral range.