We investigate reconfigurable reflected group delay in dual-band of the photonic crystal heterostructure containing phase transitions material Ge 2 Sb 2 Te 5 and graphene in mid-infrared region. The giant phase change of reflected beam derives from the topological edge state excited at the boundary surface of photonic crystal. Meanwhile, the tunable topological edge states can be satisfied by controlling the reversible switching between the crystalline and amorphous states of the Ge 2 Sb 2 Te 5 , which provides a flexible way to achieve configurable group delay in dual-band. Besides, the refle...
