Cascade Optical Parametric Amplifier Layout for High Gain and Low Noise

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Solution Overview

Problem

Optical parametric amplifiers (OPAs) face limitations in achieving high gain and output due to factors such as gain saturation, pump depression, and nonlinear effects, which hinder their application in optical communication systems.

Innovation Solution

A cascade-connected optical amplification system with multiple units, each unit featuring band division, polarization demultiplexing, excitation light multiplexing, amplification, separation, and combining units, where the first unit has lower saturation output power and higher gain than the second, optimizing the configuration to enhance overall amplification efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If optical amplifiers are inserted in optical networks to compensate for signal loss, then signal transmission distance is extended, but spontaneous emission noise is generated and accumulated

Engineering Contradiction:
Improvesignal transmission distanceVSAvoidspontaneous emission noise
Core Design Contradiction:
Length of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a variable optical attenuator as an intermediary component between the optical amplifier and the optical network. This attenuator mediates the harmful spontaneous emission noise by selectively reducing its power level while allowing the useful amplified signal to pass through, thus resolving the contradiction between extending transmission distance and suppressing noise generation

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If variable optical attenuators are used to reduce spontaneous emission noise, then noise power is reduced, but insertion loss occurs and amplifies required output power

Engineering Contradiction:
Improvespontaneous emission noise powerVSAvoidinsertion loss
Core Design Contradiction:
Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by placing the variable optical attenuator before the spontaneous emission noise becomes a dominant harmful factor in the optical network. The attenuator proactively reduces noise power at the source (the optical amplifier output) before the noise can accumulate and propagate through the network, thereby reducing the overall noise impact without requiring excessive amplification power elsewhere in the system

Inventive Principle:
Principle #10Preliminary action

3Object-generated harmful factors

If fixed optical attenuators are used to attenuate spontaneous emission noise, then noise is reduced, but insertion loss is large and power consumption increases

Engineering Contradiction:
Improvespontaneous emission noiseVSAvoidinsertion loss and power consumption
Core Design Contradiction:
Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The patent replaces fixed optical attenuators with variable optical attenuators that can dynamically adjust their attenuation characteristics. This dynamic capability allows the system to optimize the balance between noise reduction and insertion loss based on real-time network conditions, traffic demands, and signal power levels, thereby minimizing unnecessary energy loss and power consumption while maintaining effective noise suppression

Inventive Principle:
Principle #15Dynamics

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 achieves higher gain and output while maintaining low noise, overcoming limitations of individual OPAs by leveraging the complementary characteristics of cascade-connected units.

Implementation Method 1

an optical amplifier which amplifies an optical signal

Methodology Applied
Scientific EffectStimulated emission: Light

Implementation Method 2

a variable optical attenuator which varies an amount of attenuation of the spontaneous emission noise

Methodology Applied
Scientific EffectOptical absorption: Absorption (EM radiation)

Data Source

PatentEP4343422B1Optical amplification system and optical amplification method
Publication Date: 2026.04.08 NT T INC
  • EP4343422B1 patent drawingFigure 1
  • EP4343422B1 patent drawingFigure 2
  • EP4343422B1 patent drawingFigure 3

AI summary

The present invention provides an optical amplification system (1) having a plurality of cascade-connected optical amplification units (11), wherein the optical amplification units (11) comprise: a band division unit (111) that divides an optical signal into optical signals of two different bands; a polarized wave division unit (112) that divides the divided optical signals into two polarized wave components orthogonal to each other; an excitation light multiplexing unit (113) that multiplexes excitation light and the optical signals divided by the polarized wave division unit (112); an amplification medium (115) that generates an optical parametric amplification and amplifies the optical signals; an excitation light division unit (117) that divides the excitation light and the optical signals amplified by the amplification medium (115); a polarized wave synthesis unit (118) that synthesizes the two divided polarized wave components; and a band multiplexing unit (119) that multiplexes the two divided bands.