Magnetically induced Stark-like splitting and asymmetric refractive index effect in plasmonic nanostructures

Abstract

We develop an analytical method to investigate the eigenmodes of the surface plasmonic polaritons propagating along the interface of metal and magneto-optical (MO) medium by using perturbation theory. The solution shows that the MO activity can eliminate the eigenfrequency degeneracy of a pair of time-reversed waves. Analogously to the electron's magneto-Stark effect, we show this splitting can be understood as a result of “Lorentz force” acting on photons and it exhibits a Stark-like shape, which causes a difference between the forward and backward refractive index. It can be further enhanced by the surface plasmonic polaritons. Then, a hybrid structure composed with MO medium and metallic array is proposed to demonstrate this effect. In such a hybrid structure, the one-way property of surface wave presents a much higher efficiency than that of conventional magnetic photonic crystal. This Stark-like splitting at the interface of metal and magneto-optical (MO) medium can be used in the design of nanophotonic circuits, such as surface wave diode and asymmetric prism.