Investigations on the performance of distributed Raman amplifier in dense wavelength division multiplexed communication system using different modulation formats

Here, the amplification performance of distributed Raman amplifier in a dense wavelength division multiplexed (DWDM) system is analyzed. We aim to compare the performance of distributed Raman amplifier using different digital modulation formats accordant with the bit error rate (BER) and Q factor through simulations. The various pumping methods like forward pumping, backward pumping, and bidirectional pumping for different pump powers have been compared by varying the modulation formats. Binary phase shift Keying (BPSK), differential phase shift keying (DPSK), carrier suppressed DPSK (DPSK-CS), and quadrature phase shift keying (QPSK) with RZ and NRZ are analyzed as their spectral efficiency is found to be better than OOK systems. Our simulation results indicate that the bit error rates are much lesser for Raman Amplifier systems with QPSK-NRZ modulation format having SNR improvement of almost 6 dB.