A device for coupling optical signals into at least one waveguide, wherein the device comprises at least one send-site circuit, which based on incoming signals from send-site terminal contacts actuates at least one electro-optical converter, which sends out the optical signals in the direction of the axis of the waveguide, in such a way that the manufacturing expenses are low. The electro-optical converter is incorporated, in particular embedded, in at least one send-site receptacle/alignment module, the send-site receptacle/alignment module comprises at least one groove- or trough-shaped depression for aligning the waveguide in relation to the electro-optical converter, and the send-site receptacle/alignment module is, in an essentially form-fit and/or force-fit manner, incorporated, in particular fitted, in a recess provided in a send-site substrate. The corresponding is true for a device for decoupling optical signals from at least one waveguide.