Overlapping Spectrum Amplification Without C-L Band Gaps

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Solution Overview

Problem

The existing optical fiber communication systems face a reduction in data transmission capacity due to band gaps between overlapping frequency bands like C-band and L-band, resulting in a loss of valuable spectrum.

Innovation Solution

A system that splits an optical signal into two bands, amplifies them separately using erbium doped fibers, and compensates for path differences to combine them without a band gap, using a gap compensator and combiner to ensure coherent detection and reduce multipath interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the optical signal is split into separate bands (C-band and L-band) for independent amplification, then the amplification gain for each band can be optimized, but a band gap is created between the two bands resulting in spectrum loss

Engineering Contradiction:
Improveamplification gain optimizationVSAvoidspectrum loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The optical signal is divided into separate C-band and L-band components that travel through different amplification paths. This segmentation allows each band to be amplified independently with optimized gain, resolving the contradiction between achieving optimal amplification performance and maintaining continuous spectrum coverage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The delayed C-band signal and L-band signal are combined using a combiner after both have been amplified. The merging process reconstructs the full spectrum by combining the two separated bands, eliminating the band gap while preserving the optimization benefits of separate amplification paths.

Inventive Principle:
Principle #5Merging (Combining)

2Object-generated harmful factors

If the optical path lengths for different bands are made equal, then multipath interference is reduced, but the device complexity increases due to additional delay compensation components

Engineering Contradiction:
Improvemultipath interferenceVSAvoiddelay compensation components
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

A delay element is introduced in the C-band path before the signals are combined to pre-compensate for the path length difference. This preliminary action ensures that the C-band and L-band signals arrive at the combiner simultaneously, eliminating multipath interference without requiring complex real-time adjustment mechanisms.

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

The system effectively eliminates or significantly reduces band gaps between overlapping frequency bands, maintaining signal integrity and enabling efficient data transmission by coherent detection and digital signal processing.

Implementation Method 1

amplifies them separately using erbium doped fibers

Methodology Applied
Scientific EffectStimulated emission:

Implementation Method 2

delaying the first split signal by a threshold period of time relative to the second split signal

Methodology Applied
Scientific EffectTime delay:

Implementation Method 3

combining the first split signal and the second split signal, resulting in a combined signal having the first wavelength band and the second wavelength band without the band gap therebetween

Methodology Applied
Scientific EffectOptical combining:

Data Source

PatentEP3539227B1Overlapping spectrum amplification
Publication Date: 2025.12.31 GOOGLE LLC
  • EP3539227B1 patent drawingFigure 1
  • EP3539227B1 patent drawingFigure 2A
  • EP3539227B1 patent drawingFigure 2B

AI summary

A method (400) for overlapping spectrum amplification includes receiving an optical signal (102) and splitting the optical signal into a first split signal (102a) having a first wavelength band (λa) and a second split signal (102b) having a second wavelength band (λb). The splitting results in a band gap (G) between the first wavelength band and the second wavelength band. The method further includes delaying the first split signal by a threshold period of time relative to the second split signal and combining the first split signal and the second split signal, resulting in a combined signal (104) having the first wavelength band and the second wavelength band without the band gap therebetween. The path difference between the first split signal along the first signal path (P1) and the second split signal along the second signal path (P2) is within a threshold multipath interference compensation range.