Bandgap engineering of all-solid photonic bandgap fiber based on broken-ring structure

The design of an all-solid photonic bandgap fiber based on a broken-ring structure in a silica background is reported. We show by plane wave expansion calculations how the bandgap structure can be engineered and greatly expanded by replacing the high-index germanium-doped rod in a repeating cell with a ring of six individual high-index rods. Corresponding to a high-order bandgap, the designed fiber allows broad transmission of about 790nm at a center wavelength of 1550nm. The guiding mode properties and dispersion curve are also presented.