  The introduction of topology unravels a new chapter of physics. Topological
systems provide unique edge/interfacial quantum states which are expected to
contribute to the development of novel spintronics and open the door to robust
quantum computation. Optical systems can also benefit from topology.
Engineering locally in real space a honeycomb photonic crystal with double
Dirac cone in its photonic dispersion, topology transition in photonic band
structure is induced and a pseudospin unidirectional optical channel is created
and demonstrated by the backscattering immune electromagnetic transportation.
The topological photonic crystal made of dielectric material can pave the road
towards steering light propagations and contribute to novel communication
technology.
