Embodiments provide single fiber bidirectional HDCP modules. A signal fiber module includes at least one laser and at least one detector and a waveguide combiner/splitter. An optical fiber is used as a cylindrical lens in order to partially collimate in the vertical axis the optical signals entering and leaving branches of a waveguide. The branches of the waveguide have lens-shape interfaces in order to at least partially collimate in the horizontal axis the beams entering and leaving the waveguide. Each branch of the waveguide tapers toward a join-section of the waveguide. At the join section, the cross-section of a laser branch is smaller than the cross-section of a detector branch. If more than one detector is present in a module, the cross-sections of the detector branches differ from each other. If more than one laser is present in a module, the cross-sections of the laser branches differ from each other.