Silicon-chip-based real-time dispersion monitoring for 640 Gbit/s DPSK signals

We demonstrate silicon-chip-based instantaneous chromatic dispersion monitoring (GVD) for an ultrahigh bandwidth 640 Gbit/s differential phase-shift keying (DPSK) signal. This monitoring scheme is based on cross-phase modulation in a highly nonlinear silicon nanowire. We show that two-photon absorption and free-carrier-related effects do not compromise the GVD monitoring performance, making our scheme a reliable on-chip CMOS-compatible, all-optical, and real-time impairment monitoring approach for up to Terabit/s DPSK signals