Double rainbow trapping of light in one-dimensional chirped metallic-dielectric photonic crystals

We numerically show that strongly reduced group velocity and significantly long lifetime can be achieved in one-dimensional chirped metallic-dielectric photonic crystals. Since the dispersion relations are dependent on the graded thickness of the dielectric layers, light of different wavelengths can be localized at different spatial positions of the chirped structure, leading to rainbow trapping. Particularly, double trapped rainbows can be simultaneously realized in a single structure as two bandgaps appear in the dispersion curve within the analyzed wavelength range. (C) 2011 Optical Society of America