Magnetically manipulable perfect unidirectional absorber based on nonreciprocal magnetic surface plasmon

¹ Institute of Information Optics, Zhejiang Normal University - Jinhua, Zhejiang 321004, China
² State Key Laboratory of Surface Physics, Department of Physics, Fudan University - Shanghai 200433, China

^(a) syliu@zjnu.cn

Received: 5 September 2012
Accepted: 7 November 2012

Abstract

We demonstrate a design of a perfect unidirectional absorber by constructing a magnetic metamaterial (MM) made of an array of ferrite rods. Near the magnetic surface plasmon (MSP) resonance an incident transverse magnetic (TM) Gaussian beam can be absorbed completely at a particular direction, while at the symmetrically opposite direction an obvious reflected beam is observed. This unidirectionality originates from the time reversal symmetry (TRS)-breaking nature of the MM, which can also be shown numerically by comparing the scattering amplitude of the partial waves in two opposite directions. In addition, the unidirectionality can be reversed by reversing the magnetization of the ferrite rods. The working frequency can be controlled as well by tuning the external magnetic field (EMF). Another merit of this absorber is the robustness against position and size disorders of the ferrite rods.