VCO clock synchronization loop combined with dispersion equalization in optical coherent receivers

In optical coherent receivers, the timing error detector (TED) in synchronization loop can not work normally when signal is distorted by large dispersion. This paper proposes a novel clock synchronization scheme which adds a butterfly-structured adaptive equalizer to the loop to fulfill synchronizations, equalizations and polarization de-multiplexing of two polarization states simultaneously under the control of single voltage-controlled oscillator (VCO). Simulink simulation demonstrates the rationality and the feasibility of the combined loop with single VCO.