21 8 Intensity | h$_{x}$ | 2 in the transverse xy plane for a nondiffracting beam of β = 10 . 16 µ m − 1 and γ = 16 . 55 µ m − $^{1}$. Excitation of Bloch modes with | k$_{x}$ | < 5 . 15 µ m − 1 leads to nonevanescent wavelets in the dielectric slabs, so that the resulting hybrid wavefield from Eq. (5) combines Bloch constituents of different nature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 9 Transverse pattern of a nondiffracting beam with β = 9 . 00 µ m − $^{1}$. The beamwidth of the main central focus has Δ$_{x}$ = 109 nm and Δ$_{y}$ = 46 nm, going beyond the diffraction limit Δ$_{min}$ = 116 nm. . . . . . . . . . . . . . . . . . . . . . . . 31