Geometrical Tunability of Linear Optical Response of Silica−Gold Double Concentric Nanoshells

Linear optical responses of double concentric nanoshells (DCN), consisting of two alternating layers of dielectric and metal, are studied using the Mie theory and plasmon hybridization theory. Reduction of thickness either of the metallic layers or the second dielectric layer produces red-shifts of the |ω−−⟩ energy mode. A combined manipulation of these parameters can achieve an even greater shift of the surface plasmon resonance band toward the near-infrared region, favorable for biological applications. It has been demonstrated that these DCN structures have a greater geometrical tunability than the metallic nanoshells and metal−dielectric−metal structures of similar dimensions.