A lateral current injection electro-optical device includes a slab having a pair of structured, doped layers of III-V semiconductor materials arranged side-by-side in the slab, the pair including an n-doped layer and a p-doped layer, each of the p-doped layer and the n-doped layer includes a two-dimensional photonic crystal, and a separation section extending between the pair of structured layers, the separation section separates the pair of structured layers, the separation section includes current blocking trenches, and an active region of III-V semiconductor gain materials between the current blocking trenches that form a photonic crystal cavity.