Tunable plasmonic-induced transparency based on stub-coupled cascade ring resonator with electro-optical material

The electrical control of plasmonic-induced transparency (PIT) via a resonator wave-guide system is presented. The proposed structure is composed of a stub and cascade ring resonator. The ring and the stub resonator are filled with electro-optical material which can control the resonance frequency by the external voltage. Two-dimensional finite difference time domain (2D FDTD) method is used to calculate the transmission and field distribution. Single PIT is investigated both by FDTD and Coupled Mode Theory (CMT). The proposed PIT can be tuned by changing the external voltage or the geometric parameters. Double and triple PIT can be obtained by introducing more ring resonators and can be tuned by external voltage. The proposed plasmonic structure may have application in slow light device, nanoscale filter, all-optical switch and refractive index sensor.