The statement is correct. Systems operating at higher bit rates with more complex modulation formats, such as 100G using Dual-Polarization Quadrature Phase-Shift Keying (DP-QPSK), are significantly more sensitive to non-linear effects in the optical fiber (e.g., Self-Phase Modulation, Cross-Phase Modulation) than 10G systems, which typically use simpler formats like Non-Return-to-Zero (NRZ). These non-linear impairments become more severe at higher optical power levels. To balance the required Optical Signal-to-Noise Ratio (OSNR) against these detrimental non-linear effects, the optimal single-wavelength incident (launch) power for a 100G channel is engineered to be lower than that for a 10G channel.

Consequently, when upgrading an existing 10G network by adding 100G channels, the optical amplifiers (OAs) must be reconfigured. The OAs in the 10G system would have been set to provide an output power suitable for 10G signals. To accommodate the new 100G signals, the gain of the OAs can be reduced. This action lowers the total output power of the amplifier, which in turn decreases the power of each individual wavelength, bringing the 100G channels into their optimal, lower power range and preventing performance degradation from non-linearities.

The "False" option is incorrect because the statement accurately reflects fundamental principles of high-speed optical transmission and network engineering. Ignoring the need for lower launch power for 100G signals would lead to significant performance degradation due to excessive non-linear penalties. Furthermore, adjusting OA gain is the standard operational procedure for managing per-channel power levels in a WDM system.

1. Huawei Official Documentation: HCIP-Transmission V2.0 Training Material (H31-341)

Module: "WDM System Principles

" Chapter: "Key Technologies for High-Speed WDM Systems." This material explains that as the single-wavelength rate increases (e.g.

from 10G to 100G)

advanced modulation formats are used

which are more sensitive to fiber non-linear effects. To mitigate these effects

the single-wavelength launch power must be strictly controlled and is generally lower for 100G than for 10G.

2. Huawei Official Documentation: Huawei OptiX OSN 8800/9800 WDM System Network Planning Guide

Section: "Optical Power Budget and Non-linear Effect Management." The guide specifies the optimal launch power ranges for different service rates. It details that for 100G DP-QPSK signals

the launch power into a G.652 fiber is typically in the range of -1 to +2 dBm to balance OSNR and non-linear effects

whereas 10G NRZ signals can be launched at higher powers (e.g.

up to +4 dBm). The document also describes the procedure for adjusting OA gain to achieve the target per-channel power in hybrid networks.

3. Academic Publication: Agrawal

G. P. (2012). Nonlinear Fiber Optics (5th ed.). Academic Press. Chapter 9

"Wavelength-Division-Multiplexed Systems

" discusses the trade-offs in WDM system design. It mathematically and conceptually demonstrates that higher-order modulation formats have stricter power limitations due to their susceptibility to non-linear crosstalk and phase noise

necessitating lower per-channel launch power compared to simpler intensity-modulated formats.