EuroWire May 2020

Technical Article

7 References

to build 500 km transmission line, we can conclude that after the cable production, installation and splicing attenuation has increased slightly – from 0.002 dB/ km to 0.004 dB/km. We believe that such an increase can be largely attributed to splicing. For example, an average splice loss for G.652 single-mode fibres is 0.02 to 0.03 dB [5] . With an average cable length of 6 km used in our study, this results in 0.003 to 0.005 dB/km attenuation increase (if normalised per km), which is consistent with the attenuation increase observed in our measurements. Figure 6 shows how the attenuation changed after approximately one year after the deployment of the cable. No significant attenuation increase was observed, and most of the fibres showed an even lower attenuation compared to the measurements taken right after the installation. We believe that attenuation decrease can be explained by fibre relaxation in the cable after the installation, and corresponding reduction in microbend induced losses. The highest attenuation increase was less than 0.001 dB/km, which is close to the accuracy limit of OTDR. 5 Conclusions OPGW cable with ITU-T G.652-compliant ultra-low loss fibres used in this work showed excellent performance during the temperature cycling test in the lab, after field deployment and one year after deployment. Attenuation increase of the cable during the temperature cycling test was less than 0.005 dB/km at 1,550nm for temperatures in the -40°C to +85°C range. The mean value of attenuation in the installed cables including splice losses was measured to be 0.165 dB/km at 1,550nm. No significant attenuation increase was found in one year after deployment of cable. Cable design, installation procedures and low-loss optical fibre characteristics were found to be essential in achieving 100+ G unrepeatered signal transmission at distances longer than 500 km. n 6 Acknowledgements Special thanks to Igor Frolov from Saranskkabel-Optika and Test Laboratory Opticenergo for their contribution to performing the test measurements.

[1] V Gainov et al, “Record 500 km unrepeatered 1 Tbit/s (10x100G) transmission over an ultra-low loss fiber”, Optics Express 2014 Vol.22, No.19 [2] Do-il Chang et al, “Ultra-long unrepeatered transmission over 607 km at 100G and 632 km at 10G”, Optics Express 2015 Vol.23, No.19 [3] Do-il Chang et al, “Ultra-Low Loss Fiber and advanced Raman amplification deliver record unrepeated 100G transmission”, SubOptic 2016 [4] IEC 60793-2-50 Table 11 [5] ITU-T G. Sup.39_2016

Courtesy of IWCS Cable & Connectivity Symposium, Charlotte, North Carolina, USA, September/October 2019.

Corning SNG Moscow, Russia korotkovnm@corning.com www.corning.com Saranskkabel-Optikа

Saransk, Russia opgw@sarko.ru www.sarko.ru

59

www.read-eurowire.com

May 2020