Semiconductor optical amplifiers and raman amplification for 1310-nm wavelength division multiplexed transmission

We investigate the utilization of semiconductor optical amplifiers (SOAs) and quantum-dot laser-based Raman amplifiers in high-capacity dense wavelength division multiplexed (DWDM) 1310-nm transmission systems. Performed simulations showed that in a 10×40  Gbit/s 10×40  Gbit/s system, the utilization of a single Raman amplifier in a back-propagation scheme can extend the maximum error-free (bit error rate <10 −9 <10−9 ) transmission distance by approximately 25 km in comparison with the same system utilizing only an SOA used as a preamplifier. We successfully applied a Raman amplifier in an 8×2×40  Gbit/s 8×2×40  Gbit/s 1310-nm polarization multiplexed (PolMux) DWDM transmission over 25 km. Conducted experiments showed that the utilization of a Raman amplifier in this system leads to 4-dB improvement of the average channel sensitivity in comparison to the same system utilizing SOAs. This sensitivity improvement can be translated into a higher power budget. Moreover, lower input optical power in a system utilizing a Raman amplifier reduces the four-wave mixing interactions. The obtained results prove that Raman amplification can be successfully applied in 1310-nm high-capacity transmission systems, e.g., to extend the reach of 400G and 1T Ethernet systems.