Optical signal to noise ratio monitoring for ook signal using delay tap sampling

We analyze optical signal to noise ratio (OSNR) monitoring of 10-Gb/s non-return-to-zero on-off keying (NRZ-OOK) signals using delay-tap asynchronous sampling. By extracting parameters in histogram plots using polynomial fitting, OSNR is monitored from 10 dB to 30 dB. Above all, the histogram plots are obtained by fitting samples not only along the delay-tap plots diagonal but also with an appropriate angle. Effects of chromatic dispersion (CD) and polarization-mode dispersion (PMD) on the proposed technique are also investigated via numerical simulations. This OSNR monitoring method has high tolerance to CD and PMD effect for lower OSNRs (OSNR<18 dB). The measuring error is kept below 1 dB for CD up to 900 ps/nm and PMD up to 60 ps.