Page 40 - Market Analysis Report of Optical Communications Field in China & Global market 2025

Analysis of the Impact of G.654.E Fiber Cutoff
Wavelength on S-band Transmission Performance
Chen Hao¹, Wan Hong¹, John D. Downie², Lidia Galdino²
1. Chengdu Corning Cable Co., Ltd.;
2. Corning Incorporated
Abstract: This paper provides an in-depth analysis of the
transmission performance of G.654.E optical fiber in the S-band
and compares various methods for testing cutoff wavelengths.
It was found that using 22-meter cabled fiber samples yields
lower cutoff wavelengths. Modeling was carried out for G.654.
E fibers under different cable structures and deployment
conditions, and the simulation results demonstrated that higher-
order modes and multipath interference (MPI) have negligible
impact on transmission costs. Two experimental setups for S-band
transmission with G.654.E optical fibers were constructed, and
signal-to-noise ratios (SNR) were found to remain stable across
different transmission distances and baud rates, further validating mitigated by using fibers with a large effective area, such
the simulation results. These findings provide important
theoretical support and experimental validation for the practical
application of G.654.E fibers in the S-band.
Key word: G.654.E optical fiber; cutoff wavelength; S-band
transmission; higher-order modes; MPI
1. Introduction
With the continuous growth of data traffic in long-haul
trunk networks, the optical communication industry seeks
to further enhance fiber transmission capacity. According
to Shannon's theorem, capacity can be improved by either
increasing spectral efficiency (SE) or adding more signal
channels. However, SE improvements have reached a
plateau[1], leaving the expansion of channel numbers as
a more viable approach. Techniques such as multi-core
fiber (MCF) or spectrum expansion for single-core fibers
have garnered significant attention. Spectrum expansion,
which leverages existing mature systems and deployed
fibers, offers a cost-effective solution. For instance, dense
wavelength division multiplexing (DWDM) based on
the C-band and erbium-doped fiber amplifiers (EDFAs)
has been widely used for capacity enhancement. With
the accelerated deployment of 400G systems, the 400G
QPSK scheme based on the C+L band is being increasingly
used by customers. Compared to using the C-band alone,
transmission on the C+L band can double the capacity of
the fiber[2].
Following the L-band, the S-band is anticipated to become
38
the next potential extension band for long-haul transmission
systems, with research into S + C + L ultra-wideband
(UWB) transmission systems attracting considerable
attention. A challenge faced by ultra-wideband transmission
systems is stimulated Raman scattering (SRS), which
results in the transfer of optical power from the S-band
to the C and L bands, thus affecting the transmission
performance of the S-band. Research by China Mobile
indicates that the Raman power transfer from the S-band to
the L-band in G.652D fibers reaches up to 19dB[3].
System impairments in the S-band due to SRS can be
as G.654.E. Increasing the effective area of the fiber can
reduce the damage to the system caused by nonlinear
optical effects such as SRS. Compared to G.652D fibers,
G.654.E fibers reduce the Raman transfer in the S-band to
12dB, effectively improving the transmission performance
in the S-band. However, an increase in effective area results
in the cable cut-off wavelength (λCC) shifting towards
longer wavelengths, to 1530 nm. As some wavelengths in
the S-band are lower than the fiber's cut-off wavelength,
this could potentially trigger high-order mode coupling
and produce MPI, thereby affecting the transmission
performance in the S-band.
To assess the feasibility of G.654.E fibers for S-band
transmission and evaluate the impact of higher-order modes
on MPI, this study investigates the cutoff wavelength
and transmission performance of G.654.E fibers from
three key perspectives: 1)Cutoff Wavelength Testing: The
differences in cutoff wavelength measurements between
uncabled 22-meter samples (used in factory testing)
and 22-meter cabled samples (representing practical
engineering scenarios) were analyzed. The study explores
the reasons behind the changes in cutoff wavelength after
cabling and offers recommendations for cutoff wavelength
testing. 2)Modeling and Simulation: A simulation model
was developed to analyze the potential system degradation
caused by MPI when operating at wavelengths in the S-band
that are below the cutoff wavelength. 3)Experimental
Validation: An experimental system was constructed to
evaluate the S-band transmission performance of two types
of Corning G.654.E fibers (TXF® and Vascade® EX2500).
The experiments investigated the impact of G.654.E fiber