Conception de cônes de Dirac quasi-isotrope dans des cristaux photoniques unidimentionnels membranaires: Design of quasi-isotropic Dirac cones in 1D photonic crystal slabs

Dirac cones are linear dispersions located a peculiar high-symmetry point in reciprocal space. Usually, on the vicinity of these points, the dispersion is flat but can be made linear by mean of degeneracy of at least two optical modes, leading to a conical dispersion. Dirac cones provide unusual properties and have been generated in several 2D photonic crystals. This is also possible in 1D photonic crystal, however the high anisotropy of the structure geometry usually leads to high anisotropy in optical properties such as dispersion. This anisotropy can be reduced by mean of three-modes degeneracy with proper optimization. In this article, we are presenting a design of 1D photonic crystal slab exhibiting a Dirac cone with low anisotropy at X point, under the light line.