A photonic device comprising: a support; an intermediate layer comprising at least one dielectric material and a first and second excess thickness of silicon separated from each other by a space; a first patterned silicon layer at least partially forming a waveguide, and first to fifth waveguide sections; a first dielectric layer covering the first silicon layer and a gain structure comprising at least one gain medium in contact with the first dielectric layer; the second and fourth wave guide sections, the first and second excess thicknesses of silicon, and the first and second ends of the gain structure forming a first and second optical transition zone between a hybrid laser waveguide, formed by a central portion of the gain structure, the space and the third waveguide section and the first and fifth waveguide sections respectively. The invention also relates to a method of fabricating such a photonic device.