Figure 6

(a–c) calculated electric intensity distributions (in logarithmic scale) corresponding to the case of the two points M (in Fig. 5a,d) and N (in Fig. 5b,d) in addition to the case of the unperturbed PC cavity respectively. One can clearly see in (a) that the BNA pumps the PC energy and then dissipates it mainly inside the tip while the spatial extension of the cavity mode is clearly reduced in (b), compared to the unperturbed cavity in (c), due to the presence of the metal tip apex that squeezes the electromagnetic evanescent field down to the cavity. This result is consistent with the obtained discrepancy between the Q-factor of these two configurations given in Fig. 5b.