Optical By-Pass Switch for Submarine WDM Branching
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Solution Overview
Problem
Optical submarine transmission networks face challenges due to faults on branch stations, which impact the loading of WDM signals and overall transmission quality, as existing systems are not designed to handle failures effectively, leading to disruptions and reduced performance.
Innovation Solution
A branching unit configured to receive power via an optical cable, featuring an optical by-pass switch that automatically reconfigures in case of power interruptions, ensuring that traffic from one fiber can take over the capacity of another, maintaining full loading of WDM signals and reducing distortions by switching between different fiber pairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a branching unit is inserted into the optical transmission system to extract and add wavelengths, then wavelength routing capability is improved, but system complexity increases and fault vulnerability increases
Solution Approach 1:
The optical transmission system is segmented into multiple independent fiber pairs, where each fiber pair can operate independently. The branching unit is configured to switch between different fiber pairs, allowing the system to divide functionality across multiple physical paths rather than relying on a single complex routing structure.
Solution Approach 2:
The branching unit is pre-configured with multiple fiber pair inputs and outputs, establishing redundant pathways before faults occur. When a fault is detected in one fiber pair, the system can immediately switch to a pre-established alternative fiber pair without requiring complex real-time routing decisions.
2Reliability
If the entire bandwidth of WDM system is loaded to ensure good transmission through repeaters, then transmission quality is improved, but the ability to handle faults and maintain loading is reduced
Solution Approach 1:
The branching unit implements dynamic switching between different fiber pairs based on real-time fault detection. The system can adaptively reconfigure which fiber pairs are active and how bandwidth is distributed across them, allowing maintenance of optimal loading conditions even when faults occur in certain fiber pairs.
Solution Approach 2:
The system changes operational parameters by switching between different fiber pairs with different loading characteristics. When a fault occurs, the branching unit can redirect traffic to alternative fiber pairs, adjusting the distribution of WDM wavelengths to maintain full loading on operational fiber pairs while isolating faulty ones.
3Reliability
If a fault occurs on a branch of the optical submarine cable, then the negative impact on remaining traffic increases, but the ability to maintain WDM signal loading decreases
Solution Approach 1:
The branching unit is designed with redundant fiber pairs that serve as pre-prepared backup pathways. In the event of a fault in one fiber pair, the system can immediately activate alternative fiber pairs that were previously idle or underutilized, cushioning the impact of the fault on overall transmission quality without requiring complex real-time recovery decisions.
Data Source
Figure 1~2C
Figure 3A~3C
AI summary
The present document relates to optical transmission systems. In particular, the present document relates to optical submarine transmission systems. A branching unit (210) for an optical transmission system (200) is described. The branching unit (210) comprises a first and a second input port configured to be coupled to a first and a second incoming fiber (320, 321), respectively; a first output port configured to be coupled to a first outgoing fiber (322); wherein the second incoming fiber (321, 323) is part of an optical cable comprising an electrical conductor; wherein the branching unit (210) is configured to receive electrical power via the optical cable; and an optical by-pass switch (345) configured to switch between a first mode, and a second mode; wherein in the first mode, the by-pass switch (345) is configured to couple the second incoming fiber (321) to the first outgoing fiber (322); and wherein in the second mode, the by-pass switch (345) is configured to couple the first incoming fiber (320) to the first outgoing fiber (322).