Fig. 2

Characteristics of the fabricated slow light silicon PhC waveguide. a Linear transmission and b measured group index. c The calculated dispersion band from the measured group index in b. The wave vector corrected by the slope of the pump group velocity is presented. Due to very small band diagram shift the curves cannot be presented in the original form similar to Fig. 1a. Solid curve represents the original dispersion band of waveguide mode with refractive index \(n_{si}\), while the dashed curve indicates the waveguide mode with refractive index change of ≈−3 × 10⁻³. Dots indicate the locations of the input wavelengths of probe wave (red dot), pump pulse (orange dot) and the expected output wavelength of the shifted probe wave (blue dot) after the intraband transition took place. The orange line represents the phase continuity line with a slope equal to the travelling velocity of the pump pulse. Due to the slope correction, this phase continuity line now appears horizontal