Nonreciprocal Transmission under Near-zero Biased Magnetic Field

We experimentally presented electromagnetic one-way transmission in 2D magnetic photonic crystal (MPC) with only 1 Oe remnant magnetism. Such nonreciprocal edge state is independent on the degenerated point but extends from the bulk mode instead. We proved the edge state exists in both PEC and PMC boundary conditions. Distinguished from those under fully saturated magnetization, the nonreciprocal transmission in this paper requires very low, even near-zero biased magnetic field, which is flexible to implement and opens up a new avenue in nonreciprocal device design.