Furthermore, the steady state electric field intensities along the xz- plane at the middle of the structure in the y- transverse direction were calculated and are shown in Fig. 3(e–g) for the normalized operation frequencies equal to a/λ = 0.450, 0.468 and 0.496; respectively. It follows from these figures that the intensity enhancements differentiate that from the pulse excitations, as expected. Furthermore, additional localization regions occur apart from the localization region at the turning point, since the abovementioned resonator effect will give rise to a standing wave within the respective optical path. Nevertheless, the local energy density at the turning points will be higher than at the additional localization regions, as the slowing down will become maximum at these points21.