We report the recent progress in the structuration of nanoporous silicon at a submicronic scale. Multilayered periodic structures, with low-roughness interfaces, and an index contrast of 0.6 are reported. Their strong photonic bandgap properties are demonstrated by the measurement of a reflectance up to 99.64% ± 0.01%, by mean of ring-down spectroscopy.
This property is the base of a novel structure allowing an efficient guiding of light in a
low-index layer. The submicronic structuration of the optical index of a planar waveguide
along one direction of plane is also described, and a realistic map of the optical index,
demonstrating a index contrast of 0.5, is unambiguously deduced from transmission spectra.