Noise Performance Improvement of Broadband Discrete Raman Amplifiers Using Dual Stage Distributed Pumping Architecture

We demonstrate a novel design of dual stage backward pumped broadband discrete Raman amplifier with distributed pumping architecture which improves the short wavelength noise performance compared with conventional backward pumped single stage design. Overall noise figure (NF) performance has been improved by 2.8 dB over 70 nm bandwidth without introducing forward pumping. Nonlinear phase shift has been numerically calculated and compared with single stage design to evaluate the overall performance improvement. Finally, we report that our proposed dual stage design with similar to 14 dB net gain improves low wavelength NF by 3.3 dB providing 1.2 dB Q(2) factor improvement and 1134 km reach extension versus a conventional single stage design for 18 x 120 Gb/s PM-QPSK transmission.