Optical coupling of a photonic chip to an external device by use of a system with two lenses. The photonic chip comprises a light guide layer supported by a substrate and covered by an encapsulation layer, and a lens integrated into either the front face or the back face. The light guide layer includes a wave guide coupled to a surface grating coupler. An arrangement of one or several reflecting structures each on either the front face or the back face, is provided. This arrangement comprises a reflecting structure on the back face and is made so as to assure propagation of light between the surface grating coupler, and the lens along an optical path having at least one fold. The invention also covers the fabrication method of such a photonic chip.