A plasmonic resonator can include: a substrate; a central resonator on the substrate; a first curved resonator disposed on the substrate and disposed at a first side of the central resonator; and a second curved resonator disposed on the substrate and disposed at a second side of the central resonator, the first curved resonator and the second curved resonator being asymmetric to each other with respect to the central resonator, and the central resonator and at least one of the first and second curved resonators being made of different materials.
