Electromagnetic response of a compound plasmonic–dielectric system with coupled-grating-induced transparency

We propose a compound plasmonic–dielectric system consisting of one-dimension metallic gratings made of core–shell membranes and a Si grating waveguide with periodic grooves on one side, to investigate the coupled-grating-induced transparency (CGIT) effect. Both elements of the system can support certain resonant modes respectively, which have almost identical resonant frequencies but highly different quality factors, which are demonstrated by a theory model and the coupled mode theory. The electromagnetic response of the compound plasmonic–dielectric system induces coupling between these two types of gratings resonators and causes a transparency phenomenon due to the destructive interference of the resonant modes. The results show that the CGIT effect is associated with remarkable improvement of the group index corresponding to high transmission efficiency.

► We propose a compound system to investigate the coupled-grating-induced transparency effect. ► It causes a transparency phenomenon due to the destructive interference of the resonant modes. ► It is demonstrated by a theory model and the coupled mode theory. ► The effect is associated with remarkable improvement of the group index and transmission. ► This scheme provides an alternative way for plasmonic sensing and slow light applications.