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Figure 5: Experimental Setup for S-band Transmission 5. Conclusion
performance obtained when the fiber segments were This study systematically investigates the cutoff wavelength
replaced by VOA 2. The results are shown in Figures 6(a) and transmission performance of G.654.E fibers from three
through 6(d). key aspects: testing methods, MPI modeling analysis,
Figure 6(a) presents the SNR and OSNR comparisons and S-band experimental validation. The conclusions are
between transmission over 86.2 km of Vascade® EX2500 summarized as follows:
fiber and the VOA-based transmission at baud rates of 16 1) The λCC testing results based on the 22m uncabled and
G Baud and 64 G Baud. Figure 6(b) shows the performance cabled G.654.E samples indicate that the measured value of
comparison for an 81.7 km TXF® fiber link. Figure 6(c) the uncabled fiber is the maximum value of the fiber cutoff
illustrates the performance comparison for a 173.5 km wavelength. Any subsequent process, such as cabling,
Vascade® EX2500 fiber link, while Figure 6(d) provides installation, and application, will further reduce the cable's
the comparison for a 164.6 km TXF® fiber link. cutoff wavelength. Therefore, measurements based on the
22m cable sample are more practically significant reference
Figure 6: SNR and OSNR of TXF® and Vascade® EX2500 Fibers for end users. 2) Through mode coupling and intermodal
at 16 GBaud and 64 GBaud Baud Rates vs that of VOA attenuation modeling, the results show that at 1450nm,
the MPI level of the system under all cable deployment
conditions is less than -70dB/km, and MPI decreases with
the increase of the working wavelength. This distributed
MPI level causes an SNR degradation far less than 0.1dB
for long-haul systems.
3) The results of this modeling were confirmed in the
transmission experiments. The S-band signal transmission
on G.654.E fiber was tested experimentally. The
experimental results prove that G.654.E-compliant fibers
demonstrate suitability for S-band transmission with
negligible MPI penalties, and due to the lower attenuation
and larger effective area its performance is significantly
enhanced compared to G.652.D fiber.
Figure 6 shows that the SNR values measured after Reference:
transmission over fiber predominantly overlap with those [1] P. J. Winzer, K. Nakajima and C. Antonelli, "Scaling
for the VOA 2 case for every baud rate and transmission
distance, which indicates that the ASE and TRX noise Optical Fiber Capacities [Scanning the Issue]," in
are the only significant noise sources causing SNR
degradation, while the MPI effect is negligible and does Proceedings of the IEEE, vol. 110, no. 11, pp. 1615-
not further impair the SNR in all transmission scenarios.
SNR mismatches between VOA and fiber transmission 1618, Nov. 2022
lower than 0.4 dB were measured for every channel in
all transmission configurations. The maximum SNR [2] M. Cantono, R. Schmogrow, M. Newland, V.
discrepancy between the fiber and VOA transmission was
observed for the 64 GBaud 160 km TXF fiber case at 1474 Vusirikala, T. Hofmeister, “Opportunities and
nm, where the SNR was 0.39 dB lower than the VOA
2 case. However, this SNR mismatch corresponds to a Challenges of C+L Transmission Systems,” Journal of
similar OSNR difference of 0.33 dB between the VOA and
fiber transmissions, suggesting that it may result from LP Lightwave Technology, vol. 38, no. 5, pp. 1050-1060,
variations due to the polarization state of the light entering
the modulator or from a variation in the modulator bias. 1 March1, 2020
Thus, G.654.E-compliant fibers demonstrate suitability
for S-band transmission with negligible MPI penalties and [3] V. V. Ivanov, P. M. Sterlingov, S. K. Mishra, J. D.
significant performance enhancement from their lower
attenuation and larger effective area. Downie and S. Makovejs, "Effective Area Tilt Impact
In S+C+L Band Long-Haul Fiber Optic Transmission
Systems," 2022 Optical Fiber Conference
[4] Zhang Dechao “Explore the Terabit transmission
technology,” Conference on CIOE, Sep, 2024
[5] ITU-T G.Sup40 : Optical fiber and cable
Recommendations and standards guideline (10/2018)
[6] John D. Downie, Petr Sterlingov, etc.. “On the
Feasibility of S-band Transmission over G.654.E
Fiber”, ECOC2023.We.C.2.5
[7] Romulo Aparecido, Jiaqian Yang, John D. Downie,
Lidia Galdino, etc. “Experimental Demonstration of
MPI-Penalty-Free S-band Transmission over G.654.E
Fibres”,OFC2025 WE4.1 41
