Fig. 1. (a). Direct space elementary cell of the hexagonal lattice with position of two surface terminations used in this paper: on the limit of elementary cell, position 1, or in the middle of the air hole, position 2. (b) The reciprocal space with the first Brillouin zone (dotted), the incident and the specular reflected wavevectors across the circle (dashed blue) which represent the dispersion surface in silicon centered in the Γ point (0,0) of the reciprocal lattice. Red dotted circle represent the dispersion surface centered in points (1,1).

Fig. 2. Partial gaps along MM’ as a function of the hole radius. The eyes line is in correspondence of the frequency ω_n =0.289 (a). The correspondent EFS for r/a=0.31. The blue circle are EFS corresponding to the first band (0 corresponds to the lowest valence band), whereas green EFS correspond to the second band are located around the K points (b).

Fig. 3. (2.52 Mb) Movie versus time of FDTD simulation for TM polarization of an incident wave-packet modulated by Gaussian transversal profile (σ=15a) and a Gaussian longitudinal length (σ=12/λ) for a surface termination, with reference to Fig. 1, as in position 1, i.e. no cut in holes (a) and in position 2, i.e. holes cut exactly in the middle (b). [Media 1]

Fig. 4. Time average Poynting vector close to the interface between the PhC (air-holes are colored in magenta), in the upper part of figure, and the external homogenous silicon (red color). When the PhC is terminated without any holes cut the vortexes generated inside are preserved also outside the PhC (a). When the PhC is terminated in the middle of holes, where the energy flux is parallel to the interface this is preserved in the external silicon, enhancing the specular reflected beam (b).

Fig. 5. (3.07 Mb) Movie versus time of FDTD simulation for TM polarization of an incident plane wave modulated by Gaussian transversal profile (σ=15a) for a surface termination as in position 1 of Fig. 1, i.e. no cut in holes. [Media 2]