  Valley-contrast physics has gained considerable attention, particularly for
realizing photonic topological insulators (PTIs) that support reflection-free
valley-polarized edge modes (VPEMs) in the absence of inter-valley scattering.
It is an open question whether similar robust states can exist in the absence
of topological valley phase, i.e., nonvanishing Berry curvature at the valleys.
We show that a C6\u{psion}-symmetric triangular photonic crystal (PhC)
inherently exhibits uniform distribution of spatially varying phase vortices,
which support a local (limited) version of valley Hall effect (LVHE), where the
valley polarization is location defined as opposed to being fixed throughout
the bulk. We then demonstrate that defect regions with sublattice asymmetry in
otherwise a symmetric PhC lead to wave localization and splitting of photons
according to their valley index, thus enabling VPEMs along a line defect
waveguide. We fabricate our device on a silicon-on-insulator (SOI) slab and
characterize it at near-infrared frequencies showing robust transmission
through sharp bends comparable to valley PTIs. Our results present a new
perspective to creating valley edge states and outline a new waveguiding
mechanism applicable to electromagnetics as well as plasmonics, mechanics and
acoustics.
