Optical Add-Drop Element Single Amplifier Design

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Solution Overview

Problem

Existing add-drop network elements in optical communications networks are costly, especially when the number of channels to add and drop is low, due to the requirement of double stage optical amplification, which increases costs and complexity.

Innovation Solution

The proposed add-drop network element design includes a single optical amplifier, an optical coupler, and an optical splitter, along with a variable optical attenuator, to reduce costs while maintaining link budget and preventing coherent receiver overload.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If double stage optical amplification is used on the through path, then the link budget is improved and coherent receiver overload is prevented, but the cost and device complexity increase significantly

Engineering Contradiction:
Improvelink budgetVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the optical amplifier from the through path and relocates it to the add path only. This eliminates the double stage amplification complexity while maintaining link budget through alternative power management. The amplifier is taken out of the through path configuration and placed strategically in the add path to achieve the desired effect with reduced complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of the conventional approach of amplifying the through path signal (double stage amplification), the patent inverts the approach by amplifying only the add path signal. This reversal of the amplification strategy achieves the same link budget goal while avoiding the complexity of double stage amplification on the through path.

Inventive Principle:
Principle #13The other way round (Inversion)

2Power

If double stage optical amplification is used on the through path, then the signal power is maintained, but the cost increases significantly

Engineering Contradiction:
Improvesignal powerVSAvoidcost
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The patent extracts the amplifier from the expensive double stage through path configuration and relocates it to the add path. This extraction from the conventional configuration reduces the overall system cost while maintaining signal power through the alternative amplification approach in the add path only.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a single amplifier in the add path instead of expensive double stage amplification equipment. This approach uses a simpler, more cost-effective configuration that achieves the same functional result with reduced hardware investment.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If a single optical amplifier is used in the add path, then the cost is reduced, but the through path signal may be insufficient

Engineering Contradiction:
ImprovecostVSAvoidthrough path signal power
Core Design Contradiction:
Ease of manufactureVSPower

Solution Approach 1:

The patent changes the operational parameters by using a single amplifier in the add path with optimized gain settings. This parameter change allows the system to achieve the required through path signal power without needing double stage amplification, thus reducing cost while maintaining adequate signal levels.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by pre-amplifying the add path signal before it combines with the through path signal. This preliminary amplification ensures that the combined signal maintains adequate power levels throughout the system, eliminating the need for additional through path amplification stages.

Inventive Principle:
Principle #10Preliminary action

4Adaptability or versatility

If remotely reconfigurable add-drop network elements are used, then the adaptability is improved, but the cost per channel increases significantly

Engineering Contradiction:
ImproveadaptabilityVSAvoidcost per channel
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies universality by designing an add-drop network element that can serve multiple functions with a single amplifier configuration. The same amplifier structure supports both through path and add path operations, providing adaptability without requiring expensive specialized reconfigurable components for each function.

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

Solution Approach 2:

The patent merges the through path and add path amplification functions into a single amplifier unit in the add path. This consolidation provides the adaptability of handling multiple signal paths while reducing the cost per channel by eliminating redundant amplification equipment.

Inventive Principle:
Principle #5Merging (Combining)

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 design reduces costs by eliminating the need for double stage amplification, avoids overloading coherent receivers, and allows the use of simple and inexpensive coherent transceivers, making it suitable for low-cost metro and aggregation networks.

Implementation Method 1

an optical amplifier and an optical splitter. The optical amplifier comprises an input port and an output port

Methodology Applied
Scientific EffectOptical amplification:

Implementation Method 2

The optical coupler comprises an add input port, a through input port and an output port

Methodology Applied
Scientific EffectOptical coupling:

Implementation Method 3

The optical splitter comprises a drop output port, a through output port and an input port

Methodology Applied
Scientific EffectOptical splitting:

Implementation Method 4

an add-drop network element also comprises a variable optical attenuator connected to the through output port of the optical splitter

Methodology Applied
Scientific EffectOptical attenuation:

Data Source

PatentEP4122125B1Optical add-drop network element
Publication Date: 2025.02.12 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4122125B1 patent drawingFigure 1~2
  • EP4122125B1 patent drawingFigure 3

AI summary

An add-drop network element (100) for an optical communications network. The add-drop network element comprises an optical amplifier (102) having an input port and an output port. The add-drop network element comprises also comprises an optical coupler (104) and an optical splitter (106). The optical coupler (104) comprises an add input port, a through input port and an output port, the output port of the optical coupler (104) being connected to the input port of the optical amplifier. The optical splitter (106) comprising a drop output port, a through output port and an input port, the input port of the optical splitter (106) being connected to the output port of the optical amplifier.