Consistent with the present disclosure, polarized optical signals having the same wavelength are modulated in response to ERZ drive signals, to thereby yield corresponding RZ optical signals. Each of the polarized RZ optical signals includes a plurality of RZ transitions wherein the power of the optical signal returns to zero or a minimal power between bits or symbols. The phase or timing of the ERZ drive signals, however, is controlled, so that the RZ transitions in one polarized optical signal remain interleaved with the RZ transitions of the other polarized optical signal. Alternatively, the RZ transitions of the two polarized optical signals may be controlled so that the two are temporally aligned with one another. Thus, the timing of the RZ transitions of one polarized optical signal relative to the other polarized optical signal may be adjusted to optimize system performance.