WDM-PON Seed Light Module Spectrum Slicing
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Solution Overview
Problem
Conventional WDM-PON systems experience loss of optical power during the spectrum slicing process when using a broadband light source, limiting the increase of seed light beyond a predetermined level.
Innovation Solution
A WDM-PON system employing a spectrum-sliced external seed light module, which includes an erbium-doped optical fiber, pump light source, optical coupler, and wavelength demultiplexer/multiplexer, to generate and transmit high-power seed light without loss through the optical wavelength multiplexer, and incorporates an optical wavelength conversion device at the subscriber side for wavelength conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a broadband light source is used and spectrum slicing is performed through a WDM MUX, then multiple wavelengths can be generated, but optical power loss occurs during the spectrum slicing process
Solution Approach 1:
The patent performs spectrum slicing before the light enters the WDM MUX by using an optical filter in the seed light generation unit. This preliminary action divides the broadband light into multiple wavelength components before multiplexing, allowing the WDM MUX to operate without causing additional power loss during the slicing process.
Solution Approach 2:
The patent introduces an optical filter as an intermediary component between the broadband light source and the WDM MUX. This optical filter acts as a mediator that performs the spectrum slicing function, enabling the WDM MUX to focus on wavelength multiplexing without the penalty of power loss.
2Length of moving object
If external seed light is used to increase optical power, then transmission distance and quality are enhanced, but conventional WDM-PON systems still experience power loss during spectrum slicing
Solution Approach 1:
The patent implements preliminary spectrum slicing in the seed light generation unit before the light traverses the WDM MUX. This ensures that when external seed light is used to enhance transmission distance, the power loss that would normally occur during spectrum slicing is prevented, as the slicing is completed before the light enters the multiplexer.
3Adaptability or versatility
If a WDM-PON system uses spectrum-sliced light through a WDM MUX, then wavelength division multiplexing is achieved, but the system cannot accommodate conventional G-PON and E-PON ONUs
Solution Approach 1:
The patent designs the optical line termination unit to perform multiple functions: it can operate in conventional G-PON/E-PON modes without wavelength conversion, and also support WDM-PON mode with wavelength conversion when needed. This multi-functionality allows the system to accommodate both conventional ONUs and WDM-capable ONUs, providing universality across different network configurations.
Solution Approach 2:
The patent implements dynamic configuration capability where the optical line termination unit can switch between different operational modes (conventional mode and WDM mode) based on the requirements of connected ONUs. This dynamic adaptability allows the system to accommodate different types of ONUs without requiring separate dedicated systems.
4Productivity
If dense wavelength division multiplexing is used in feeder fibers, then transmission efficiency is improved, but the system becomes more complex and harder to implement
Solution Approach 1:
The patent segments the wavelength management function into separate components: the seed light generation unit handles spectrum slicing, the optical line termination unit handles wavelength conversion and multiplexing, and the optical network unit handles reception and transmission. This segmentation allows each component to be optimized independently, reducing overall system complexity while maintaining high transmission efficiency through dense wavelength division multiplexing.
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 prevents power loss during spectrum slicing, enhances transmission distance and quality by injecting high-power seed light, and allows for the use of dense wavelength division multiplexing in feeder fibers while accommodating conventional TDMA-PON units, reducing the need for feeder fibers and lowering costs.
Implementation Method 1
a seed light module located at the central office, and for supplying a spectrum-sliced seed light including a plurality of wavelengths to corresponding optical transmitters of the optical line termination
Implementation Method 2
the light transmitted from the BLSs is spectrum-sliced as it passes through an optical wavelength multiplexer (WDM MUX) included in the OLT and an optical wavelength multiplexer (WDM MUX) mounted at a remote node (RN)
Implementation Method 3
an optical wavelength conversion device located at the subscriber side, and for wavelength-converting upstream and downstream signals into signals of different bands
Data Source
AI summary
The present invention proposes a wavelength division multiplexing-passive optical network (WDM-PON) system which transmits downstream data to an optical network unit (ONU) as an optical line termination (OLT) receives seed light from a spectrum-sliced external light source module. One characteristic of the proposed WDM-PON system is that optical transmitters of the OLT and ONU are operated regardless of optical wavelength. Another characteristic of the proposed WDM-PON system is that a conventional TDMA-PON (E-PON or G-PON) ONU can be accommodated without a change.