Optical Add-Drop Multiplexer Asymmetrical Filtering for Flexible Routing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional Optical Add-Drop Multiplexers (OADMs) lack flexibility in routing wavelength channels due to symmetrical filtering profiles, leading to limitations such as reduced port usage, cross talk, and multi-path interference, especially in Combine-and-Route configurations.

Innovation Solution

Implementing asymmetrical filtering profiles in OADMs, where the multiplexer and demultiplexer filters are offset by one channel wavelength, allowing independent processing of individual channels within a group, thereby doubling the number of degrees without increasing hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If symmetrical filtering profiles are used in conventional OADMs, then the filtering is simple and hardware requirements are met, but routing flexibility is reduced and cross talk occurs

Engineering Contradiction:

Improverouting flexibilityVSAvoidcross talk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by configuring the multiplexer filter and demultiplexer filter with different central frequencies. Specifically, the multiplexer filter has a central frequency offset by one channel wavelength relative to the demultiplexer filter, creating asymmetrical filtering profiles that enable independent channel processing and eliminate cross talk between adjacent channels.

Inventive Principle:

Principle #4Asymmetry

2Adaptability or versatility

If symmetrical filtering profiles are used, then hardware configuration is straightforward, but channels within a group must be treated together reducing port usage

Engineering Contradiction:

Improveport usageVSAvoidfilter configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements asymmetry in filter configuration where the multiplexer filter central frequency is deliberately offset by one channel wavelength from the demultiplexer filter central frequency. This asymmetric arrangement allows channels within a group to be independently added, dropped, or passed through, effectively doubling the number of usable ports without increasing hardware complexity.

Inventive Principle:

Principle #4Asymmetry

3Adaptability or versatility

If asymmetrical filtering is implemented, then routing flexibility is doubled, but filter configuration complexity increases

Engineering Contradiction:

Improvedegrees of freedomVSAvoidfilter offset configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the frequency parameter of the filters to resolve the contradiction. By offsetting the multiplexer filter central frequency by exactly one channel wavelength relative to the demultiplexer filter, the system achieves doubled routing flexibility while maintaining manageable configuration complexity through a standardized frequency offset relationship.

Inventive Principle:

Principle #35Parameter changes

4Object-affected harmful factors

If conventional symmetrical OADMs are used, then the system is simple to operate, but multi-path interference occurs requiring guard bands

Engineering Contradiction:

Improvemulti-path interferenceVSAvoidbandwidth

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The asymmetric filter configuration eliminates multi-path interference by ensuring that the multiplexer filter does not pass channels that were filtered by the demultiplexer. The one-channel-wavelength offset creates non-overlapping filter responses that prevent signal leakage and eliminate the need for guard bands, thereby preserving full bandwidth.

Inventive Principle:

Principle #4Asymmetry

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 enhances routing flexibility, reduces cross talk and multi-path interference, and eliminates the need for guard bands, while maintaining bandwidth and reducing chromatic dispersion, effectively doubling the number of ports in OADM nodes.

Implementation Method 1

a demultiplexer having a first filter configured to: pass the first wavelength channel and the second wavelength channel, and filter the third wavelength channel

Methodology Applied

Scientific EffectWavelength selective filtering: Filter (optical)

Implementation Method 2

a multiplexer having a second filter configured to: pass the second wavelength channel and the third wavelength channel, and filter the first wavelength channel

Methodology Applied

Scientific EffectWavelength selective filtering: Filter (optical)

Data Source

PatentUS20250233681A1Optical add drop multiplexers with asymmetrical filtering

Publication Date: 2025.07.17 EQUINIX INC

AI summary

This disclosure describes techniques for Optical Add Drop Multiplexers (OADMs) that apply asymmetrical filtering to allow for individual channels within a channel group to be independently added/dropped or passed through. In one example, an optical add-drop multiplexer includes a first input port configured to receive an input signal having a first wavelength channel, a second wavelength channel, and a third wavelength channel; a demultiplexer having a first filter configured to: pass the first wavelength channel and the second wavelength channel, and filter the third wavelength channel; a multiplexer having a second filter configured to: pass the second wavelength channel and the third wavelength channel, and filter the first wavelength channel; and a first output port configured to output an output signal comprising the second wavelength channel of the input signal.