Topologically protected vector edge states and polarization beam splitter by all-dielectric valley photonic crystal slabs

The polarization beam splitter (PBS) is the essential optical component, which is widely used in various optical instruments. Its robustness against perturbation is very necessary to all-optical classical and quantum networks. Here, we report the design of topologically protected vector edge states (dual-polarization with transverse electric and transverse magnetic modes) and PBS based on all-dielectric topological valley photonic crystal slabs. The topologically protected vector edge states have been realized for the first time using germanium photonic crystal slab with silica substrate. Based on such edge states, the topologically protected PBS has been designed and its robust property has been demonstrated by exact numerical simulations. Our proposed PBS is expected to be widespread applications for photonic integrated circuits and quantum information processing.