The invention relates to a device (100a, 100b, 100c, 100d, 100e, 100f) for coupling optical signals into at least one waveguide (10), which device comprises at least one electro-optical converter (28), which emits the optical signals in the direction of the axis or of the core (12) of the waveguide (10). In order to further develop said device in such a way that active alignment of the waveguide (10) is not required, the receiving-side optical subassembly (80) according to the comprises at least one guide channel (86) for aligning the waveguide (10) in relation to the optoelectrical converter (68), in particular in relation to the inlet opening or active surface (70) of the electro-optical converter (68), and the optoelectrical converter (68) is accommodated, in particular embedded, in at least one receiving-side optical subassembly (80). The same applies, accordingly, to a device (140) for coupling optical signals out of at least one waveguide (10).