Double plasmon induced transparency in disk and nanobars coupled nanosystems and its application to plasmonic resonance sensing

We demonstrate the realization of plasmon induced transparency (PIT) in a nanostructure composed of silver nanobars and a silver nanodisk. The optical properties of the planar metamaterials have been investigated theoretically in the paper. The classical coupled harmonic oscillator model demonstrates the PIT phenomenon in a nanodisk–nanobar system. Additionally, double PIT response is observed when two nanobars are located in proximity to the silver nanodisk. The PIT window wavelength and bandwidths can be efficiently tuned by controlling the geometric parameters such as the lengths of nanobars and the coupling distances between the nanodisk and nanobars. Moreover, the transparency window shows highly sensitive response to the refractive index of the environmental medium. A high figure of merit up to 15.5 of the asymmetrical system for refractive index sensing is achieved. The tunability of the PIT may have potential application on slow light and highly integrated optical circuits.