Photonic Crystal Slabs
The radiational eigenmodes in photonic crystal slabs are classified into guided and leaky modes. The former are genuine eigenmodes with infinite lifetimes, while the latter are quasi-eigenmodes with finite lifetimes. We will show that the dispersion curves of photonic crystal slabs are well represented by the folding of those in uniform dielectric slabs into the two-dimensional Brillouin zone. This feature enables us to predict the symmetries of the eigenmodes by group theory. The optical transmission due to the leaky modes in the direction parallel to the slab surface is mainly governed by their diffraction loss, which is a particular feature of photonic crystal slabs. We will show that the diffraction loss is suppressed by symmetry mismatching between internal eigenmodes and the external radiation field [81, 82].
KeywordsHexagonal GaAs Mirror Symmetry
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