A system includes a first device and a second device. The first device generates a source optical signal using a first optical signal and a polarization splitter-rotator. The second device modulates the source optical signal from the first device using a first data signal to produce a first modulated optical signal. The first modulated optical signal has a polarization that is orthogonal to a polarization of the source optical signal. The first device recovers the first data signal from the first modulated optical signal using at least the polarization splitter-rotator.