Mode splitting of surface plasmon resonances in super-period metal   nanohole gratings
  We experimentally observed the surface plasmon resonance mode splitting in a super-period metal nanohole grating under the transverse magnetic polarization excitation. The mode splitting was observed in the zeroth order transmission and also in the first order diffracted transmission. However, the mode splitting phenomenon is more evident in the first order transmission than in the zeroth order transmission. It is explained that the mode splitting is due to the coupling between the surface plasmon resonance mode in the subwavelength period metal nanohole arrays and the resonance mode of the metal super-grating. 
Junpeng Guo and Haisheng Leong
physics.optics cond-mat.mes-hall physics.ins-det