[13p-N321-1~15] 3.11 Photonic structures and phenomena

▼ [13p-N321-4] Light transmission in triangular lattice photonic crystal waveguides with 120-degree sharp bends

〇Wei Dai¹, Taiki Yoda², Yuto Moritake^1,3, Masaaki Ono^2,4, Eiichi Kuramochi^2,4, Masaya Notomi^1,2,4 (1.Tokyo Tech, 2.NTT BRL, 3.JST PRESTO, 4.NTT NPC)

Keywords:photonic crystal, topological photonics

Valley photonic crystals (VPhCs) can be constructed by breaking the inversion symmetry of the bulk lattice. Two VPhCs connected by an interface, as a photonic crystal waveguide (PhCWG), can support valley-polarized states of light, which are reported to travel robustly through 120-degree sharp bends with suppressed corner reflection. Since the broken inversion symmetry is the heart of valley photonic properties, we compare the light transmission through 120-degree bends using PhCWGs with and without the inversion symmetry to investigate its influence. Surprisingly, we observed high transmission through 120-degree sharp bends in PhCWGs with the inversion symmetry. We found that the presence of the inversion symmetry does not cause significant differences in terms of the transmission through 120-degree bends. We report both the theoretical and the experimental results.