Furukawa Electric Co., Ltd. has increased the quality of optical signal transmission at 800Gbps in the C+L band using an optical transmission system equipped with a Forward Raman Unit.
Raman amplification
Raman amplification is a supporting technology in optical fiber communication systems, and backward-pumped Raman amplification, which amplifies optical signals from the receiver side, is used normally.
There were high expectations for forward Raman units given the broad bandwidth of the optical output and low noise characteristics, but the development of a low-noise optical pump source was an issue.
noise amplification characteristics
In March 2023, FUrukawa solved this issue with forward-pumped Raman amplification (Fig. 1) and confirmed bidirectionally pumped Raman amplification with low noise amplification characteristics applicable for practical optical fiber communications systems (Fig. 2).
The optical noise characteristics of the transmitted optical signal were low enough, that Furukawa could expect a better quality of the optical signals (Q factor.)
Quality of optical signals
The bandwidth of the Forward Raman Unit amplification has been expanded from only the C band to the C+L band, and the output signal quality was measured by transmitting an optical signal at 800Gbps (100Gbaud dual polarization 16QAM), which is the next-generation communications speed, over a distance of 150km in C+L band through a standard optical fiber for transmission.
Furukawa measured the Q factor, which indicates the quality of an optical signal, of the optical signal amplified through bidirectionally pumped Raman amplification using the Forward Raman Unit and confirmed improvement of the Q-factor by 0.5dB compared to that under backward pumped Raman amplification and by 1.0dB compared to that using standard optical amplification (EDFA: Erbium Doped Fiber Amplifier) (Fig. 3).
transmission capacity
Bidirectionally pumped Raman amplification using the Forward Raman Unit will contribute to a larger transmission
Bidirectionally pumped Raman amplification using the Forward Raman Unit will contribute to a larger transmission capacity under the same transmission length.
This would impact future optical fiber communication systems. This new development will be reported at OFC 2024 held on March 24-28, 2024 in San Diego (March 27, 2024 (Wednesday) at 16:30-16:45 (local time), W4D.1), and the Forward Raman Unit will be exhibited (OFS Fitel, LLC booth; Booth number 2041).
environmentally friendly networks
Also, the current research results were obtained as part of the National Institute of Information and Communication Technology (NICT) commissioned research (JPJ012368C04501).
Furukawa will continue our efforts to increase the performance of the Forward Raman Unit support the advancement of telecommunications society and realize all photonics networks tied together fully by light. Through this, Furukawa will contribute to establishing socially and environmentally friendly networks.
