Fig. 1. (a) Dielectric-NIMM interface. NIMM (in the lower half-plane, x<0) has frequency-dependent permittivity ε1 and permeability μ1. Dielectric (in the upper half-plane, x>0) has frequency-independent permittivity ε2 and permeability μ2. SPP propagates along z-direction; (b) Im(β) (blue solid line) and Re(1/k2) (red dashed line) as functions of oscillating frequency ω.

Fig. 2. Im(β) of the SPP as a function of ω at the dielectric–NIMM interface (blue solid line) and the dielectric–metal interface (red dashed line). Im(βNIMM)=3.16  cm−1 (blue dot) and Im(βmetal)=29.73  cm−1 (red dot) at ω=ωp=2π×3.8462×1014  s−1.

Fig. 3. (a) Intensity profile of the Airy-type SPPs at the dielectric–NIMM interface; (b) intensity profile of the Airy-type SPPs at the dielectric–metal interface; (c) maximum intensity max(|u|2) as a function of z in free-space (blue solid line), the dielectric–NIMM interface (red dashed line), and the dielectric–metal interface (green dash–dot line). Parameters are taken as l0=3  μm and a=0.005. Other parameters are the same as those used in Fig. 2.