Energy-per-Bit Analysis of S+C+L-Band Optical Links Using Doped-Fibre and Raman Amplification

We investigate the power consumption of ultra-wideband SCL-band transmission systems using hybrid amplification. We measure the electrical-to-optical power conversion efficiencies of commercial EDFAs and TDFAs and distributed Raman amplification (DRA) pumps. We use the closed-form Gaussian Noise (GN) model including ISRS alongside these measurements to investigate the energy-per-bit of hybrid amplification under backward-DRA pump and launch power optimisation. Our results show that the S-band plays a critical role in the energy-efficiency of UWB systems, due to a combination of low TDFA efficiency, power depletion from inter-channel stimulated Raman scattering and large GFF power overheads. In short links, DRA provides only nominal throughput gain and the energy-per-bit increases for all DRA pump configurations. However, in the long-haul regime (>1000 km) the throughput gain provided by DRA offsets the increased power consumption, resulting in up to 10% reduction in the total energy-per-bit. Taking into account the power consumption of a typical pluggable transceiver, we show that if the total transceiver power consumption exceeds that of the amplifiers, or if the power consumption overheads are large, DRA becomes an energy-per-bit efficient amplification technique for high-capacity ultra-wideband systems.