Page 46 - Market Analysis Report of Optical Communications Field in China & Global market 2018

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New ultra-low loss & large effective area single-mode

fiber for next-generation terrestrial

transmission network

R&D Center Zhang Lei
Yangtze Optical Fibre and Cable Joint Stock Limited Company
T he standard G.652.D optical fiber are widely deployed in Chinese Figure 1 Schematic diagram for optical fiber refractive index profile structure

terrestrials network, while most of the optical cable laid in 1990s
and have reached 20 --25 years’ service life. With the rapidly development
of 400G or beyond 400G system, the backbone network optical fiber
should be upgraded gradually in the next few years. Therefore, how to
choose the right optical fiber for the long-distance terrestrial optical
cable is a key problem urgent to be solved for the network operators and
optical communication companies. In order to obtain the best system
performance, if we can combine the ultra-low attenuation and large
effective area characteristics into an optical fiber, such optical fiber will
be the best optical fiber in the next-generation communication optical effective area optical fiber products are more competitive in the cost.
fiber.
3. Product performance
1. Latest G.654.E Recommendation 3.1 Optical fiber attenuation
G.654 fiber has widely used in submarine cable since 1990s, its lower In terms of theory and practical points of view, the lower attenuation
loss and larger effective area characteristics are more suitable for can reduce the number of repeaters and reduce the maintenance costs of
next generation 400G system. But submarine cable deployment and long-haul communication network. Therefore the continuous reduction
application conditions are quite different to terrestrial cable. So ITU-T in the optical fiber attenuation is the long-term goal of optical fiber
decides to make a new subclass for terrestrials G.654 fiber and titled research and development. For optical fiber R&D and manufacturing
as G.654.E fiber. The following table shows the latest ITU-T G.654 enterprises, if we can carry out the qualitative and quantitative analysis
specification and YOFC ultra-low loss large effective area optical fiber on various parts composed by the attenuation in theory, it can effectively
datasheet. Compared to G.654.B&D, the new G.654.E specification has help us find the best way to reduce attenuation and guide our work
tightened MFD and dispersion range and pays more attention to macro- direction in the practical work.
bending performance. Due to the complicated deployment condition of
terrestrial cable, the macro-bending requirement of G.654.E is as same as The following table shows the specific comparison value for each loss
G.652.D fiber. As shown in the table1, the ultra-low loss & large effective contribution factors of the ultra-low loss and large effective area optical
area optical fiber (FarBand®Ultra) of YOFC can meet and even be better fiber and the standard G.652.D optical fiber’s attenuation contribution
than the most existing stringent G.654.E standard recommendation by different parts at 1550nm. Thanks to the pure silica core design by
proposals. PCVD process, the Rayleigh scattering can be lower to about 0.12dB/km
Table 1. ITU-T G.654 fiber specification and YOFC G.654 series fiber and YOFC ultra low loss fiber’s typical can reach to 01.5dB/km.
datasheet.
Figure 2 Standard G.652.D and ultra-low attenuation optical fiber attenuation
spectral decomposition

3.2 Macro-bending loss
Another factor affecting the use of large effective area optical fiber on
land is that the terrestrial cable installation and application environment
are more complex than the submarine cable, it often needs to go through
some of the corners or needs to leave enough cable or fiber length in the
junction box, therefore, we must ensure that the terrestrial optical fiber
has better macro-bending resistance performance than the submarine
optical fiber.

2.Design and manufacturing of optical fiber The main factor affecting the macro-bending is the profile design of the
YOFC ultra-low loss & large effective area optical fiber used pure silica optical fiber. The depressed trench structure is the main design scheme
concept in the manufacturing and compared with the traditional used for bend-insensitive G.657 optical fiber, while in our ultra-low loss
fluorine-doped external cladding structure ULL fiber, YOFC adopts pure large effective area optical fiber design, we use a similar structure, which
silica (SiO2) as the optical fiber outer cladding. Due to the reduction can optimize the volume of the depressed trench to a reasonable value
in the use amount of fluorine-doped materials, in terms of material in order to obtain a better bending resistance performance. As shown
preparation cost, preparation technology difficulty, environmental in the following figure, compared with the standard G.652.D single-
protection and other points of view, our ultra-low attenuation large mode fiber, our ultra-low loss large effective area optical fiber has more
excellent bending insensitive performance; it can fully meet and be better
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