Embodiments include methods for connecting a stack of waveguide layers to a face of a ferrule presenting a mechanical alignment structure. The method includes bringing a ferrule in an alignment position and dispersing glue in cavities of mechanical alignment structure for each waveguide layer. The method also includes sliding the waveguide layer into the cavities, inserting a comb-like tool in the ferrule so that the tool presses the waveguide layer into the cavities, glue curing the ferrule, and adding a cover to the ferrule. The mechanical alignment structure comprises mechanical alignment slots arranged in a bidirectional lattice structure.