SEARCH Articles Figures Tables Bandgap Bandgap Expansion Photon Emission and Absorption Bandgap photons transfer electrons Defects, photonic bandgap materials Hollow-core photonic bandgap fibers Photonic bandgap crystal Photonic bandgap fibers Photonic bandgap materials Photonic bandgap materials pattern Photonic bandgap microcavity Photonic bandgap structures Refractive index, photonic bandgap Refractive index, photonic bandgap materials