All-optical clock recovery from 40 Gbit/s NRZ signal based on clock line enhancement and sharp periodic filtering

40 GHz clock extraction from a common 40 Gbit/s NRZ signal is experimentally demonstrated. First, a nonlinear optical preprocessor is exploited and then a semiconductor-assisted Fabry-Perot filter is used for clock extraction. The good performance and stability of the recovered 40 GHz clock signal is confirmed when it is used in a 40 Gbit/s back-to-back bit error ratio measurement.