The photonic bandgap properties of centered rectangular dimer cylinder structures are reported. The theoretical model is inspired by a crystalline phase found for colloidal self-assembly of asymmetric dimers. The band structures, as a function of degree of lobe fusion and degree of lobe symmetry, are calculated in accordance with the tunable features resulting from seeded emulsion polymerization synthesis. The parameters are varied incrementally from single circular cross section cylinders to lobe-tangent dimer cylinders. Odd, even, and polarization-independent gaps in the guided modes are found for direct and inverted slab structures. A wide range of shape parameter combinations supported relative gap widths up to 19.1% (3–4 odd gap) and 14.6% (1–2 even gap) in direct structures having low to moderate Brillouin zone distortion from the hexagonal. Slab thickness was tuned to overlap even and odd mode gap frequency ranges, generating a 9.9% polarization-independent gap. The results are compared with those from model centered rectangular slabs having dimer particle bases that limit the slab height. Inverted slab structures yielded a large maximum 40.4% 1–2 even mode gap and for up to 25% Brillouin zone distortion still supported significant gaps ().
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