A photonic integrated circuit chip includes vertical grating couplers defined in a first layer. Second insulating layers overlie the vertical grating coupler and an interconnection structure with metal levels is embedded in the second insulating layers. A cavity extends in depth through the second insulating layers all the way to an intermediate level between the couplers and the metal level closest to the couplers. The cavity has lateral dimensions such that the cavity is capable of receiving a block for holding an array of optical fibers intended to be optically coupled to the couplers.