Directionless ROADM Using Segmented Wavelength Selective Switches
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Solution Overview
Problem
Current ROADM systems are not directionless, requiring manual reconnection of transceivers to switch between degrees, and large N×N cross-connects are costly and difficult to install, especially for multi-degree nodes with many wavelengths, leading to high up-front costs and installation challenges.
Innovation Solution
A directionless reconfigurable optical add/drop multiplexer system using 1×N wavelength selective switches, splitters/combiners, optical amplifiers, and tunable filters, allowing for scalable, non-blocking, and flexible deployment with reduced fiber interconnects by combining splitter/combiner modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large N×N cross-connects are used to enable directionless ROADM functionality, then dynamic transceiver reconfiguration to arbitrary degrees is achieved, but system cost and installation complexity increase significantly
Solution Approach 1:
The patent segments the large N×N cross-connect into multiple smaller 1×N wavelength selective switches, where N represents the number of degrees. Each WSS handles a specific wavelength range and can be independently controlled, breaking down the monolithic complex device into manageable modular units that collectively provide the same directionless reconfiguration capability.
Solution Approach 2:
The wavelength selective switches are designed to perform multiple functions: they can route wavelengths to different degrees, filter specific wavelengths, and dynamically reconfigure connections. This multi-functionality reduces the need for separate dedicated components for each function, thereby lowering overall system complexity and cost while maintaining adaptability.
2Quantity of substance
If the number of degrees and wavelengths per fiber increases to support more channels, then channel capacity increases, but the size of required cross-connect grows quadratically making installation and servicing difficult
Solution Approach 1:
Instead of using a single large cross-connect that grows quadratically with channel capacity, the patent segments the routing function across multiple smaller WSS units. Each WSS handles a subset of wavelengths and can be independently installed, configured, and serviced, making operations scalable and manageable even as channel capacity increases to support dozens of wavelengths across multiple degrees.
3Reliability
If redundant switch fabric is added to ensure network availability, then system reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent implements dynamic redundancy where the WSS units can be rapidly reconfigured through software control to provide alternate routing paths. Instead of static redundant hardware that doubles the switch fabric complexity, the system uses dynamic programmability of the WSS devices to create redundant paths on-demand, improving reliability while maintaining manageable device complexity through intelligent control rather than hardware duplication.
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 provides a cost-effective, scalable, and flexible directionless ROADM system that is compatible with existing technologies, offering lower up-front costs and non-blocking functionality for high channel counts, reducing fiber interconnects and enabling dynamic transceiver reconfiguration without manual reconnection.
Implementation Method 1
1×N wavelength selective switches (WSS)
Implementation Method 2
optical amplifiers
Implementation Method 3
tunable filters which selects out a particular wavelength for drop
Data Source
AI summary
The present invention provides a directionless reconfigurable optical add/drop multiplexer (ROADM) system. The present invention provides a scalable all-optical switching element that includes a combination of 1×N wavelength selective switches (WSS), 1×N splitters/combiners, optical amplifiers, and tunable filters to provide a fully non-blocking solution which can be deployed in a scalable manner. The 1×N splitters are configured to split multiples copies of a plurality of drop wavelengths which can be amplified and sent to a tunable filter which selects out a particular wavelength for drop. The 1×N combiners are configured to combine multiple add wavelengths for egress transmission.