One Way Light Transmission through metal membranes
  We propose a new mechanism for irreversibility of light assisted by surface plasmon polaritons (SPPs). By achieving the different mutual conversion efficiency between the radiation field and the SPPs on the opposite surfaces of metal membrane, the unidirectional transmission is observed in a quite simple asymmetric metallic sub-wavelength structures Ag(15nm)/AAO, in which the difference of the two-way transmittance is large than 50%. 
Hai Wang, Yun-Song Zhou, Shan-Shan Zhang, He Wang, Guo-Zhong Zhao,   Zhi-Peng Li, Pei-Jie Wang and Hong-Wei Jiang
physics.optics