Simple monitoring technique for synchronised phase remodulation using narrowband optical filtering

Synchronised phase remodulation (SPRM) to erase the original and write the new phase information simultaneously is a crucial signal processing technique in optical networks. A simple and polarisation-insensitive monitoring scheme for SPRM using a narrowband optical bandpass filter (OBPF) is demonstrated. Experiments show that, with the optimal central wavelength of the OBPF, -1.2 and 3.8 dB monitoring power dynamic ranges are obtained for non-return-to-zero differential phase shift keying and return-to-zero DPSK formats, respectively, thus achieving high monitoring sensitivity