Optical Amplifier Filtering for In-Band and OOB OSC Links
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Solution Overview
Problem
Existing optical supervisory channel (OSC) solutions in wavelength division multiplexing systems face limitations in bit-rate and distance coverage, requiring additional hardware for in-band (IB) or out-of-band (OOB) OSC, which is costly and space-consuming, especially in amplified WDM multi-hop links.
Innovation Solution
An optical amplifier apparatus with integrated IB and OOB add/drop filtering capabilities, enabling flexible OSC selection based on span length, using first and second optical drop filters to handle OOB and IB OSC signals within or outside the amplifier's bandwidth, respectively, and an optical add filter to combine OSC with service channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If in-band OSC is used to cover longer distances with optical amplification, then distance coverage is improved, but hardware complexity increases due to required external filter boxes at amplifier nodes
Solution Approach 1:
The patent combines the OSC add/drop filtering functionality with the existing DWDM filtering capabilities of the optical line amplifier node. The OSC add/drop filters are integrated into the existing filter structure that already handles service channels, eliminating the need for separate external filter boxes and reducing hardware complexity while maintaining long-distance coverage capability.
Solution Approach 2:
The optical line amplifier node is designed to handle both service channels and OSC signals through a unified filtering and amplification structure. The same filter bank and amplifier infrastructure that processes WDM service channels is also used for OSC signal add/drop and amplification, making the node universally capable of handling multiple signal types without requiring dedicated separate hardware.
2Device complexity
If out-of-band OSC is used for short spans, then hardware cost is reduced, but distance coverage is limited
Solution Approach 1:
The system dynamically adapts its OSC handling capability based on the actual span requirements. The integrated filter structure can selectively process OOB OSC signals for short spans or IB OSC signals for long spans, allowing the hardware to flexibly adjust its behavior to match the operational needs of each specific link without requiring different hardware configurations.
3Reliability
If dedicated SOA modules are used to amplify OOB OSC wavelength, then link budget is improved, but cost and space requirements increase
Solution Approach 1:
The OSC signal amplification is merged with the existing EDFA amplification infrastructure. Instead of using separate SOA modules, the OSC signal is amplified by the same EDFA that amplifies the service channels, utilizing the existing pump lasers and gain medium. This eliminates the need for additional expensive SOA modules while maintaining adequate link budget through the shared amplification resource.
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
Provides a universal solution for OOB and IB OSC signals, optimizing OSC selection per-span, reducing hardware requirements, and enabling cost-effective deployment across various span lengths without additional hardware.
Implementation Method 1
The first optical drop filter is configured to drop from an incoming optical signal an out-of-band, OOB, OSC signal at a wavelength outside the optical amplifier operating bandwidth
Implementation Method 2
The second optical drop filter is configured to drop from an incoming optical signal an in-band, IB, OSC signal at a wavelength within the optical amplifier operating bandwidth
Implementation Method 3
The optical amplifier has an input, an output and an operating bandwidth that includes the WDM channel wavelength grid
Implementation Method 4
The optical add filter is configured to add an outgoing OOB OSC or IB OSC signal to a plurality of service channel signals at channel wavelengths of the WDM channel wavelength grid to form the outgoing optical signal
Data Source
AI summary
Optical amplifier apparatus (100) comprising: an input (102) for an incoming optical signal (IN) comprising an optical supervisory channel, OSC, signal and service channel signals at channel wavelengths of a WDM channel wavelength grid; an output (112) for an outgoing optical signal (OUT); an optical amplifier, OA, (106) having an operating bandwidth including the WDM channel wavelength grid; a first optical drop filter (104) configured to drop from an IN signal an out-of-band, OOB, OSC signal at a wavelength outside the OA operating bandwidth; a second optical drop filter (108, 208) configured to drop from an IN signal an in-band, IB, OSC signal at a wavelength within the OA operating bandwidth; an OSC signal output (114) configured to output the dropped OSC signal; an OSC signal input (116) configured to receive an outgoing OOB OSC or IB OSC signal; and an optical add filter (110, 210) configured to add an outgoing OOB OSC or IB OSC signal to service channel signals at channel wavelengths of the WDM channel wavelength grid to form the OUT signal.