(a–d) Fabrication process: (a) adhesive bonding of the AlGaAs epitaxy on a silicon substrate; (b) GaAs substrate removal; (c) HSQ resist spun and patterned by electron beam lithography; (d) ICP RIE etching; (e) Ring resonators and bus waveguides; (f) SEM pictures of fabricated devices: (top left) bus waveguide and ring resonator in the evanescent coupling region; (top right) fabrication test of longitudinal corrugated PhC waveguides for dispersion engineering; (bottom left) waveguide end facet; (bottom right) SW grating coupler. (g) Optical transmission of a ring resonator and (h) its associated group index n _g , calculated for each resonances (blue scatters) and fitted in function of λ (red dashed line).