A coupling module includes optical couplers that are coupled to waveguides. The optical couplers are configured to couple to cores of a multi-core optical fiber. The waveguides each include an external part extending from the module and an internal part extending into the module for connecting the external part to the associated optical coupler. The external part of some of the waveguides extends in a preferential direction, while the external part of others of the waveguides extends in a direction opposite to the preferential direction. The internal parts may include a curved portion configured for forming a turn-back.