Fig. 1. Calculation of the dispersion relation of the W1 waveguide by 3D FDTD simulation for both TE (a) and TM polarization (b). In both figures, the solid dots represent the simulation results. (a) For TE polarization, the continuous curves represent the suggested dispersive modes. In the TE crystal bandgap, between ω=0.425 and 0.510 (575–690nm), two modes are allowed to propagate. They are denoted even and odd by their in-plane symmetry. The shaded region depicts the crystal modes. (b) For TM polarization, the band diagram is dominated by crystal modes. The index guided waveguide mode and dominant crystal slab mode are drawn in red (solid and dashed lines, respectively). These bands are identified by mode solving and correspond to the modes with the lowest temporal decay in the FDTD simulation.

Fig. 2. Image sizes: 41 µm×4 µm (a) SEM image of the W1 waveguide under investigation. (b,c) Result of a near-field measurement on a PhCW with λ=674 nm. (b) Measured distribution of Acosϕ. (c) Normalized distribution of the amplitude of the evanescent optical field.

Fig. 3. Measured photonic band diagram of the W1 PhCW. Spatial Fourier Transforms (SFTs) of the measured A cosϕ of the optical field along the waveguide direction. The SFTs are represented by a linear false-color scale at their corresponding optical frequencies. Peaks represent the resonant wavevectors in the waveguide. The calculated dispersion relations of the TE modes are plotted in blue. The even and odd waveguide modes (TE polarization) are represented by the dashed blue lines. The index guided TM modes (waveguide and crystal) are both indicated by dashed green lines. Finally the light line (ω=ck_x ) is drawn in solid black.

Fig. 4. Group velocity determined by measurement of the propagation distance through the waveguide as a function of pulse delay. The squares and solid circles represent measurements at wavelengths 612 nm and 675 nm respectively. The straight lines are linear fits through the data. The group velocity found at λ=612 nm is c/(2.0±0.6). For the red-shifted pulse at 675 nm, the group velocity is c/(3.4±0.4).