We theoretically and experimentally study the Rabi splitting induced by photon tunneling modes in a paired structure
composed of a permittivity-negative medium and a permeability-negative medium. It is shown that a tunneling mode
will appear at the frequency where the paired structure is equivalent to a media with effective (near) zero refractive
index. A cavity may be realized with features: subwavelength cavity size and exponentially increasing of the optical
field. Therefore, the photon tunneling mode in a metamaterial with effective (near) zero refractive index may be used as
a cavity with highly localized field and small volume.
In this paper, the tunneling phenomenon occurring in a pair structure consisting of epsilon-negative (ENG) and
mu-negative (MNG) metamaterials is investigated. First, the ENG and MNG metamaterials are fabricated using coplanar
waveguide loading with lumped-element series capacitors and shunt inductors. Then, the tunneling phenomenon
occurring in the ENG-MNG pair is experimentally demonstrated. Finally, the properties of the tunneling mode are
studied and the results show that the tunneling frequency is independent of the pair length and the electric field of the
tunneling mode is highly localized at the interface of the ENG-MNG pair.
The light localization due to defects and disorder and its effects on light propagation in one-dimensional (1D) photonic band gap (PBG) structures is studied numerically with transfer matrix method. For a defect layer embedded at the center of a I D PBG structure, the simulation results indicated that, the photons will be trapped in the defect region. For a disordered I D PBG structure, a mechanism for extension of the transmission band gap is illustrated with combining the effects of Bragg reflection and Anderson localization. We propose that, analog to disordered semiconductors, there may exist two band gaps in disordered PBG structure: transmission gap and mode-density gap.