Topological polarization selection concentrator.

Topological polarization selection devices, which can separate topological photonic states of different polarizations into different positions, play a key role in the field of integrated photonics. However, there has been no effective method to realize such devices to date. Here, we have realized a topological polarization selection concentrator based on synthetic dimensions. The topological edge states of double polarization modes are constructed by introducing lattice translation as a synthetic dimension in a completed photonic bandgap photonic crystal with both TE and TM modes. The proposed device can work on multiple frequencies and is robust against disorders. This work provides a new,to the best of our knowledge, scheme to realize topological polarization selection devices, and it will enable practical applications such as topological polarization routers, optical storage, and optical buffers.