Fig. 1. SOI SPhCW covered by a cladding material of nclad index. (a) Geometry with the parameters shown: nSi=3.48, nSiO2=1.44, nclad=1.52, r1=120  nm, r=105  nm (radius of all holes outside the two first rows); (b) influence of the slowing-down factor (nG) on the confinement properties of SPhCW designed for the integration of materials of index ∼1.5: dielectric energy confinement (ηclad) of the W1-like and true-slot modes; (c) and (d) dispersion diagrams for WS=80  nm, WS=200  nm, respectively. Additionally, insets give the real-space Ey-field component distributions of the three modes at k=0.5×2πc/a in linear scale. Fields are normalized to carry a unitary mode dielectric energy.

Fig. 2. Dielectric energy confinement in the low-index material (ηclad) of silicon SPhCWs studied through the SOI SPhCW configuration described in Fig. 1 at the edge of the Brillouin zone: (a) true slot mode and (b) W1-like mode.

Fig. 3. Bragg-like corrugated SPhCWs. (a) Description of the waveguide geometry; (b)–(d) dispersion diagrams obtained for a 50/150 nm corrugated slot in which wide parts are aligned with the two nearest neighboring holes (dx=0) for r1=110, 125, and 140 nm, respectively (all other parameters being identical to the one described in Section 1, including r2=105  nm).

Fig. 4. Strong influence of the r2 parameter on the frequency splitting between the two even-mode symmetry slot modes: (a) dispersion diagram obtained for r1=140  nm and r2=95  nm (see Section 1 for a complete description of all other parameters; the two arrows are an identification of the two studied modes); (b) wavelength splitting between the true-slot and W1-like modes as a function of r2.

Fig. 5. Adjustment of the dispersive properties of the corrugated SPhCW by the r2 parameter: (a) group index and GVD proprieties (β2) for the r2=115  nm configuration; (b) evolution of the SPhCW “flat band slow light” normalized delay product of the true slot mode as a function of the diameter of the second row of holes (r2).