Plasmon-induced transparency in metal-insulator-metal waveguide side-coupled with multiple cavities.

We have demonstrated the analogue of electromagnetically induced transparency (EIT) in the metal-insulator-metal plasmonic waveguide, which consists of a bus waveguide side-coupled with a series of slot cavities. By finite-difference time-domain simulations, it is found that the resonance wavelength of the slot cavity can be controlled by adjusting the length of the cavity. Moreover, the EIT-like response is strongly dependent on the coupling separation between the corresponding adjacent cavities. Multiple-peak plasmon-induced transparency can be realized by cascading multiple cavities with different lengths and suitable cavity-cavity separations. This ultracompact plasmonic waveguide system may find important applications for multichannel plasmonic filter, nanoscale optical switching, and slow-light devices in highly integrated optical circuits and networks.