K p 0 π - π 2 π 0 2 π 2 4 6 8 k p FIG. 2. Dispersion equation at ω = 3 . 4 × 10 15 rad / s for a periodic media as represented in Fig. 1 with w = 5 × 10 − 8 m and p = 4 . 5 × 10 − 7 m. The red lines marks the boundary of homogeneous-wave and evanescent-wave regimes in the dielectric, k$_{‖}$p = 7 . 711. 24