Compact Mode-Wavelength Selective Switch for SDM-WDM Signals

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Solution Overview

Problem

Current optical communication systems face challenges in efficiently demultiplexing Space-Division Wavelength Division multiplexed (SDM-WDM) optical signals due to high losses and complexity associated with the use of Single-Mode Fibers (SMF) in the demultiplexing process.

Innovation Solution

The proposed Mode-Wavelength Selective Switch (MWSS) employs a mode separator module and an array of beam steering mirrors to selectively route and redirect SDM-WDM optical signals directly within the MWSS, eliminating the need for intermediate SMF processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mode-demultiplexer is used to convert MMF signal into multiple mono-mode signals transmitted to SMF, then the optical signals can be demultiplexed, but propagation losses and system complexity increase significantly

Engineering Contradiction:
Improvesignal demultiplexing capabilityVSAvoidpropagation losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent combines the mode-demultiplexing function and wavelength-selective switching function into a single integrated device. The mode separator module and WSS are merged into one compact structure, eliminating the need for separate SMF transmission paths and reducing overall system complexity while maintaining signal demultiplexing capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention extracts the demultiplexing function from the traditional SMF-based approach and implements it directly within the MMF using the mode separator module. This extraction eliminates the intermediate conversion step to mono-mode signals and their transmission through SMF, thereby reducing propagation losses.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If a mode-demultiplexer converts MMF signal into multiple mono-mode signals through SMF, then signal separation is achieved, but device complexity increases

Engineering Contradiction:
Improvesignal separation capabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the mode separator module with the wavelength selective switch into a single integrated device. This combination eliminates the need for separate demultiplexing equipment and SMF infrastructure, reducing device complexity while maintaining effective signal separation capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated device performs multiple functions simultaneously: it separates spatial modes, separates wavelengths, and routes signals. This multi-functionality replaces what would traditionally require multiple separate devices, thereby reducing overall system complexity.

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

3Ease of operation

If traditional two-step demultiplexing is used with SMF, then optical signals can be selectively transmitted, but the system becomes less compact and more complex

Engineering Contradiction:
Improvesignal selective transmissionVSAvoidsystem configuration
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines mode separation and wavelength-selective switching into a single compact device that maintains full signal selective transmission capability. The integrated architecture preserves operational flexibility while eliminating the complexity of separate demultiplexing equipment and SMF connections.

Inventive Principle:
Principle #5Merging (Combining)

4Adaptability or versatility

If MMF signals are converted to mono-mode signals via SMF, then wavelength selection can be performed, but propagation losses increase

Engineering Contradiction:
Improvewavelength selection capabilityVSAvoidpropagation losses
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The invention extracts the wavelength selection function and implements it directly within the MMF using an integrated WSS. This eliminates the need to convert signals to mono-mode and transmit them through SMF, thereby maintaining wavelength selection capability while reducing propagation losses.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The mode separator module and wavelength selective switch are merged into one device, allowing wavelength selection to be performed on the MMF signals directly after mode separation, without requiring intermediate SMF transmission and reducing energy losses.

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 approach enables high-performance, compact, and efficient selective transmission of SDM-WDM optical signals, reducing propagation losses and system complexity while maintaining high capacity and flexibility.

Implementation Method 1

a mode separator module configured to separate spatially the input optical signals into at least two intermediate optical signals

Methodology Applied
Scientific EffectSpatial mode separation:

Implementation Method 2

an array of beam steering mirrors configured to redirect the intermediate optical signals inside the MWSS, at least one of the intermediate optical signals being redirected towards the at least one output path

Methodology Applied
Scientific EffectLight reflection and beam steering: Reflection

Data Source

PatentEP4542274A1Compact mode-wavelength selective switch and roadm for SMF/MMF/MCF fibers
Publication Date: 2025.04.23 NOKIA SOLUTIONS & NETWORKS OY
  • EP4542274A1 patent drawingFigure 1~2
  • EP4542274A1 patent drawingFigure 3~4
  • EP4542274A1 patent drawingFigure 5~6

AI summary

A Mode-Wavelength Selective Switch (MWSS) (10) comprising: - at least one input path (12) for receiving input optical signals (20) combined using space division multiplexing in an input optical fiber (14) supporting several spatial modes or containing multiple cores, - at least one output path (16) for emitting an output optical signal (22) in an output optical fiber (18), - a mode separator module (24) configured to separate spatially the input optical signals (20) into at least two intermediate optical signals (28); and - an array of beam steering mirrors (26) configured to redirect the intermediate optical signals (28) inside the MWSS (10), at least one of the intermediate optical signals (28) being redirected towards the at least one output path (16).