Reach Extension of a DPSK Optical Link Using an Optical Filter Demodulator and MLSE Receiver

We have proposed a novel scheme based on chirped fiber Bragg grating (CFBG) as a narrowband optical filter demodulator and a maximum likelihood sequence estimation (MLSE) receiver to attain an enhanced unrepeatered reach in a nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) transmission link. An extended reach up to 500 km with only 2-dB optical signal-to-noise ratio penalty is found feasible for a 10.7-Gb/s NRZ-DPSK link with the CFBG-MLSE combination.