On-Chip Multiple Electromagnetically Induced Transparencies in Photon-Plasmon Composite Nanocavities

Chip-integrated multiple electromagnetically induced transparencies are realized using a photon-plasmon composite nanocavity (composed of a single photonic crystal nanocavity coupled with a single plasmonic nanocavity), i.e., comprehensively utilizing the superiorities of photonics as well as plasmonics. The destructively interferential coupling of one broad-band plasmonic nanocavity mode with two narrow-band silicon photonic crystal nanocavity modes generates two electromagnetically induced transparency windows. The two transparency windows simultaneously have a narrow line width of 15 nm, a high transmission contrast of 70%, and a strong slow light effect. A large group refractive index of more than 400 is obtained at the transparency window center, indicating a 10-fold increase in comparison with earlier results. The photon-plasmon composite nanocavity has a feature size of only 2 mu m. The transparency window shifts 30 nm for the photon-plasmon composite nanocavity covered with a monolayer of graphene excited by a -30 V external voltage. The strategy offers one approach to constructing multifunctional integrated photonic circuits.