Passive Wavelength Cross-Connect for Optical Networks

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Solution Overview

Problem

All-optical networks that use optical cross-connects (OXCs) face limitations such as slower switching speeds, higher optical power losses, higher costs, and increased wavelength contention, making it difficult to manage reliability and latency, especially with dynamic provisioning and burst traffic.

Innovation Solution

The implementation of passive wavelength cross-connects (PWXCs) using only passive optical components to couple switchable wavelength connects (SWCs), which redirect even and odd-numbered wavelength channels without active or electrical components, enabling rapid switching and avoiding wavelength contention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If optical cross-connects (OXCs) are used to route optical signals, then network connectivity and routing capability are improved, but switching speed decreases and latency increases

Engineering Contradiction:
Improvenetwork connectivityVSAvoidswitching speed
Core Design Contradiction:
Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent replaces active optical cross-connects (which require electrical control and signal processing) with a passive wavelength cross-connect that uses purely optical wavelength-based routing. This substitution eliminates the need for electrical-to-optical conversion and active control mechanisms, thereby maintaining network connectivity while dramatically improving switching speed and reducing latency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the routing parameter from electrical/control-based switching to wavelength-based routing. By using different wavelength channels to identify different routing paths, the system achieves faster switching speeds since wavelength selection is an inherent property of the optical signal rather than requiring external control signals.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If optical cross-connects (OXCs) are used for signal routing, then routing flexibility is improved, but optical power loss increases

Engineering Contradiction:
Improverouting flexibilityVSAvoidoptical power loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent replaces active OXC components that require power consumption for signal switching and regeneration with passive optical components. The passive wavelength cross-connect uses wavelength-division multiplexing and passive optical filtering to route signals, eliminating the need for active power-consuming switching mechanisms while maintaining routing flexibility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The passive wavelength cross-connect enables signals to self-route based on their wavelength characteristics. Each wavelength channel automatically follows its designated path through the passive optical network without requiring active control or power consumption, thereby reducing overall system power loss while maintaining routing capabilities.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If optical cross-connects (OXCs) are deployed, then network functionality is improved, but system cost increases

Engineering Contradiction:
Improvenetwork functionalityVSAvoidsystem cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive active optical cross-connect hardware with a passive wavelength cross-connect architecture. By eliminating the need for costly electrical control circuits, power supplies, and active switching components, the system achieves comparable or superior network functionality at a lower manufacturing and deployment cost.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The passive wavelength cross-connect provides multiple routing functions simultaneously through wavelength-division multiplexing. A single passive device can handle multiple wavelength channels with different routing destinations, replacing what would traditionally require multiple active switching units, thereby reducing overall system cost while maintaining comprehensive network functionality.

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

4Difficulty of detecting and measuring

If traditional optical networks use electrical switching functions, then signal processing capability is improved, but latency increases and efficiency decreases

Engineering Contradiction:
Improvesignal processing capabilityVSAvoidlatency
Core Design Contradiction:
Difficulty of detecting and measuringVSLoss of time

Solution Approach 1:

The patent replaces electrical switching and signal processing functions with purely optical operations in the passive wavelength cross-connect. Wavelength-based routing and optical filtering perform signal processing tasks without requiring electrical-to-optical conversion, thereby maintaining signal processing capability while eliminating the latency introduced by electrical intermediate steps.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The passive optical network maintains continuous optical signal flow without interruption for electrical conversion. Signals traverse the network entirely in the optical domain, with wavelength-based routing providing continuous guidance without the start-stop nature of electrical switching, thereby reducing latency and improving efficiency.

Inventive Principle:
Principle #20Continuity of useful action

5Adaptability or versatility

If optical cross-connects are used with dynamic provisioning, then service flexibility is improved, but wavelength contention increases

Engineering Contradiction:
Improveservice flexibilityVSAvoidwavelength contention
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the resource allocation parameter from time-domain switching to wavelength-domain routing. By assigning specific wavelength channels to specific routing paths and services, the system eliminates wavelength contention that occurs in traditional OXCs where multiple signals compete for the same switching resources. Service flexibility is maintained through wavelength assignment while contention is eliminated.

Inventive Principle:
Principle #35Parameter changes

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 solution results in higher switching speed, lower optical power loss, lower latency, and reduced costs, supporting burst-mode traffic without the need for dynamic optical power management, while increasing the number of nodes and improving network efficiency.

Implementation Method 1

The PWXC comprises one or more cascaded Mach-Zehnder interferometers (MZIs)

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP3656133B1All-optical networks based on switchable wavelength connects (SWCS)
Publication Date: 2022.10.05 HUAWEI TECH CO LTD
  • EP3656133B1 patent drawingFigure 1
  • EP3656133B1 patent drawingFigure 2
  • EP3656133B1 patent drawingFigure 3~4

AI summary

An all-optical network comprises: a first network; a second network; and a PWXC coupling the first network to the second network and comprising passive optical components. A method comprises: receiving a first optical signal from a first tail node of a first network; directing the first optical signal from a first input port of a PWXC to a first output port of the PWXC using first passive optical components; and transmitting the first optical signal to a third head node of a third network. An all-optical network comprising: a light bank; a first network coupled to the light bank; a second network coupled to the light bank; and a first PWXC coupling the first network and the second network.