Optical Branching Device WSS Redundancy Loopback

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Solution Overview

Problem

Existing optical branching/coupling devices for submarine cable systems face challenges in achieving high reliability and long-term performance due to the complexity and cost associated with integrating wavelength selective switches (WSS), which are critical for reconfigurable optical add/drop multiplexing functions.

Innovation Solution

The optical branching/coupling device incorporates a configuration with multiple splitting and switching mechanisms, including wavelength selecting means and crossbar switching, to ensure reliable operation even when one or both WSS units are faulty, utilizing a loopback unit to maintain signal transmission across different terminal stations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If wavelength selective switches (WSS) are integrated into the optical branching/coupling device to enable reconfigurable optical add/drop multiplexing functions, then the adaptability and wavelength switching capability are improved, but the device complexity and development cost increase

Engineering Contradiction:
Improvewavelength switching capabilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The optical branching/coupling device is divided into multiple independent WSS units (first WSS unit and second WSS unit), each capable of performing wavelength selection independently. This segmentation allows the system to maintain wavelength switching capability while isolating failures to individual units, thereby managing overall device complexity through modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each WSS unit is designed to perform multiple functions: wavelength selection, signal routing, and backup operations. The first and second WSS units can both handle wavelength switching for different wavelength bands, providing universal functionality that maintains system adaptability while enabling redundancy

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple WSS units are configured in the optical branching/coupling device to ensure operation even when one or both WSS units are faulty, then the reliability is improved, but the device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system configures both first and second WSS units in advance as backup resources. When a WSS unit fails, the system can switch to the other unit that has been prepared beforehand, ensuring continuous operation without requiring complex real-time reconfiguration or external backup systems

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

When one WSS unit fails, the system discards the faulty unit and recovers functionality by switching to the operational unit. The failed unit can be isolated and replaced without affecting the overall system, allowing for easy maintenance and recovery of full functionality

Inventive Principle:
Principle #34Discarding and recovering

3Reliability

If a loopback unit is added to maintain signal transmission across different terminal stations when WSS units fail, then the reliability is improved, but the device complexity and cost increase

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The loopback unit acts as an intermediary component that redirects signals when WSS units fail. It provides a backup path for signal transmission between terminal stations, ensuring continuous communication without requiring complex reconfiguration of the entire network infrastructure

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The loopback unit is pre-configured to automatically activate when WSS units fail. This preliminary setup ensures that signal transmission can be maintained immediately upon failure without requiring complex real-time decision-making or system reconfiguration

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances the reliability of the optical branching/coupling device, allowing it to maintain performance and functionality over long periods, even with WSS failures, thereby meeting the requirements for submarine cable systems with extended performance guarantees.

Implementation Method 1

a wavelength selective switch (WSS) used in a land system

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

combine signals switched to a specific port into a wavelength division multiplexing (WDM) signal

Methodology Applied
Scientific EffectWavelength division multiplexing:

Implementation Method 3

the input signal is split into at least two parts

Methodology Applied
Scientific EffectOptical splitting:

Implementation Method 4

the circulators in turn coupled to first central couplers

Methodology Applied
Scientific EffectOptical coupling:

Data Source

PatentEP3790206B1Optical branching/coupling device and optical branching/coupling method
Publication Date: 2023.06.07 NEC CORP
  • EP3790206B1 patent drawingFigure 1
  • EP3790206B1 patent drawingFigure 2
  • EP3790206B1 patent drawingFigure 3

AI summary

An optical branching/coupling device includes: a first optical branching unit that splits first light with a first and a second wavelength , and outputs second light and third light; a wavelength selector that receives the second light , receives fourth light with a third wavelength , output fifth and sixth light, one of the fifth light and the sixth light including an optical signal of the first wavelength of the second light and including the fourth light, and the other including an optical signal of the second wavelength; a first light switch that receives the fifth light and the sixth light, output one of the fifth light and the sixth light as seventh light, and output the other as eighth light; and a second light switch that receives the third light, receives the eighth light, and outputs the third or the eighth light that have been input as ninth light.