Time-Diversity Coherent Receiver Using Single Optical Coupler

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Solution Overview

Problem

Existing coherent optical communication systems experience signal power loss due to the need for separate optical couplers for polarization folding and phase-diversity splitting, which increases complexity and power consumption.

Innovation Solution

A time-diversity coherent receiver system utilizing a single optical coupler to perform both polarization folding and signal phase-diversity splitting, reducing signal loss and system complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate optical couplers are used for polarization folding and phase-diversity splitting, then the system can perform both functions, but signal power loss increases and device complexity increases

Engineering Contradiction:
Improvefunctional capabilityVSAvoidsignal power loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent combines polarization folding and phase-diversity splitting functions into a single optical coupler structure. This merged coupler simultaneously performs both polarization folding (combining X and Y polarized signals) and phase-diversity splitting (separating in-phase and quadrature components), eliminating the need for separate optical couplers and reducing signal power loss associated with multiple coupling stages.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single optical coupler is designed with multi-functionality to perform both polarization folding and phase-diversity splitting operations. This universal component replaces what would traditionally require two separate specialized components, achieving functional versatility while reducing system complexity and energy loss.

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

2Adaptability or versatility

If separate optical couplers are used for polarization folding and phase-diversity splitting, then both functions can be performed, but device complexity increases

Engineering Contradiction:
Improvefunctional capabilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges two separate optical coupler functions into a single integrated coupler structure. This consolidation reduces the number of components, simplifies the overall system architecture, and decreases the complexity associated with managing multiple optical paths and coupling stages while maintaining both polarization folding and phase-diversity splitting capabilities.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If a single optical coupler performs both polarization folding and phase-diversity splitting, then signal loss is reduced and complexity is lowered, but the coupler must perform multiple functions simultaneously

Engineering Contradiction:
Improvesignal power lossVSAvoidcoupler complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The single optical coupler is designed with multi-functionality to perform both polarization folding and phase-diversity splitting operations. This universal component replaces what would traditionally require two separate specialized components, achieving functional versatility while reducing system complexity and energy loss.

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

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 solution reduces power loss and system complexity by enabling simultaneous polarization folding and phase-diversity splitting with a single optical coupler, facilitating more efficient data transmission and lower operational costs.

Implementation Method 1

an optical coupler configured to perform both polarization folding and signal phase-diversity splitting

Methodology Applied
Scientific EffectPolarization folding: Polarisation

Implementation Method 2

the transmitted signal is interfered with using a local oscillator (LO) such that phase information can be extracted

Methodology Applied
Scientific EffectOptical interference: Interference

Data Source

PatentEP4539361A1Time-diversity polarization-folding coherent optical technology for optical communication
Publication Date: 2025.04.16 GOOGLE LLC
  • EP4539361A1 patent drawingFigure 1
  • EP4539361A1 patent drawingFigure 2A
  • EP4539361A1 patent drawingFigure 2B

AI summary

The technology is generally directed to a time-diversity coherent receiver that reduces power loss associated with using polarization folding to perform spatial diversity to time-diversity conversion. The signal power loss is reduced by using a single optical coupler to perform both joint polarization folding and signal phase-diversity splitting. The optical coupler may receive a first signal portion and a second signal portion from a polarization beam splitter, wherein one of the signal portions has first passed through a time delay module configured to delay said portion by a symbol period or multiple symbol periods. The optical coupler may recombine and fold the first and second signal portions. The output of the optical coupler may be a first combined signal component and a second combined signal component. The first and second combined signal components may be polarization-folded signals. The first and second combined signal components may be transmitted to other optical couplers as part of the receiver.