Photonic modes of a chain of nanocylinders by the embedding method

The photonic band structure of a linear array of metallic nanocylinders is calculated using the embedding method. The coupling to the vacuum on either side of the array is treated exactly, allowing the continuum states and plasmon broadening above the light-line to be treated accurately. In addition to the plasmon bands, which broaden at larger cylinder radius, there are two guided modes, with the character of surface plasmon polaritons. These split off the light-line at small wave-vector, becoming almost dispersionless as they enter the plasmon bands. The electric fields associated with the modes are calculated, and their symmetries are discussed.