Rotation-configured topological phase transition in triangle photonic lattices

Photonic topological edge states have shown powerful capabilities to manipulate light propagations. In particular, the all-dielectric structures serve as a promising platform to support the topological states, in which the nontrivial photonic band is usually acquired by engineered shape and lattice with isotropic structures. Here, we propose to manipulate the topological phases in two-dimensional (2D) triangle photonic lattices composed of anisotropic pillars. It is found that the rotation of pillars or unit cells, accompanied by complex coupling effects, can infuse degrees of freedom to switch the photonic band structure between trivial and nontrivial topological phases. We further work out a 2D phase diagram describing the rotation-induced topological transition and demonstrate polarization-dependent robust one-way light propagations in silicon at telecommunication wavelength. This work proposes an alternative scheme to manipulate the topological phases and nontrivial photonic states, which promises more interesting explorations of on-chip light manipulation.