An optical communications device has light transmitters of a first wavelength that are coupled to a number of first waveguides of an optical data link, respectively. A second set of light transmitters of a second, different wavelength are coupled to another set of waveguides of the link, respectively. The light transmitters are to transmit data from the same data processing element that is to use the link to communicate with another data processing element. The device also has a set of light detectors of the first wavelength that are coupled to the second set of waveguides, respectively. Another set of light detectors of the second wavelength are coupled to the set of first waveguides, respectively. Other embodiments are also described and claimed.