Optical Interconnection Device for WDM PON Upgrades
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Solution Overview
Problem
Implementing WDM transmissions in client devices of optical networks poses challenges in wavelength control and stability, inventory size, and cost, particularly in upgrading from EPON to WDM-overlaid PON systems.
Innovation Solution
The use of a black-and-white optical layer in the last segment of the optical access network enables standardization and mass-production of client terminals, with direct modulation laser sources for high-capacity transmission and an optical interconnection device featuring upstream and downstream conversion sections with wavelength converters for efficient wavelength management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If WDM transmissions are implemented in client devices, then transmission capacity is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an optical interconnection device as an intermediary component between the central optical node and client terminals. This device performs wavelength conversion functions, allowing client terminals to use simple black-and-white lasers while the interconnection device handles the complex WDM wavelength management, thus resolving the contradiction between transmission capacity and device complexity
Solution Approach 2:
The patent extracts the wavelength conversion function from client terminals and places it in a separate optical interconnection device. This separation allows client terminals to remain simple while the interconnection device handles the complex wavelength management, enabling WDM capacity without increasing client device complexity
2Productivity
If WDM transmissions are implemented in client devices, then transmission capacity is improved, but inventory size and cost increase
Solution Approach 1:
The patent makes client terminals universal by using standard black-and-white laser sources that can be mass-produced. The optical interconnection device handles the wavelength-specific functions, allowing the same client terminal design to serve multiple wavelength channels, thus reducing inventory size while maintaining high transmission capacity
Solution Approach 2:
The optical interconnection device acts as a mediator that enables a single type of client terminal to interface with multiple wavelength channels. This intermediary handles the wavelength conversion, allowing universal client terminals to achieve WDM-capable transmission without requiring multiple different device types, thereby reducing inventory requirements
3Measurement precision
If wavelength conversion is performed at client terminals, then wavelength control is improved, but device complexity increases
Solution Approach 1:
The optical interconnection device serves as an intermediary that performs wavelength conversion with precise control. This separates the wavelength control function from the client terminal, allowing high-precision wavelength management in the interconnection device while keeping client terminals simple
Solution Approach 2:
The patent extracts the wavelength control function from client terminals and concentrates it in the optical interconnection device. This extraction allows sophisticated wavelength management without complicating the client terminal design, as the control functionality resides in the intermediary device
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 simplifies the manufacturing and deployment of client terminals, reduces costs, and achieves high-capacity WDM transmission without the need for colorless ONUs, enabling easy upgrade of GPON networks with reduced complexity and inventory requirements.
Implementation Method 1
converting the first downstream optical signal from the first wavelength channel of the frequency grid to a downstream black-and-white wavelength channel
Data Source
Figure 1~3
Figure 2
Figure 4
AI summary
A method for transmitting modulated optical signals between a central optical node and a first and a second optical client terminals, the method comprising at an optical interconnection device (10): receiving the upstream optical signals carried by an upstream black-and-white wavelength channel (λ1) through client optical links (9) and converting the upstream optical signals to wavelength channels (λ2, λ3) of a frequency grid for WDM transmission to the central optical node through a central optical link (3), converting the downstream optical signals from wavelength channels (λ6, λ7) of the frequency grid to a downstream black-and-white wavelength channel (λ10) and transmitting the downstream optical signals carried by the downstream black-and-white wavelength channel to the optical client terminals through the client optical links (9).