Partial bandgap characteristics of parallelogram lattice photonic crystals are proposed to suppress the radiation modes in a compact dielectric waveguide taper so as to obtain high transmittance in a large wavelength range. Band structure of the photonic crystals shows that there exists a partial bandgap. The photonic crystals with partial bandgap are then used as the cladding of a waveguide taper to reduce the radiation loss efficiently. In comparison with the conventional dielectric taper and the complete bandgap photonic crystal taper, the partial bandgap photonic crystal taper has a high transmittance of above 85% with a wide band of 170 nm.
© 2009 Chinese Optics Letters
Jin Hou, Dingshan Gao, Huaming Wu, and Zhiping Zhou, "Compact and broadband waveguide taper based on partial bandgap photonic crystals," Chin. Opt. Lett. 7, 309-311 (2009)