Multi-Wavelength Fiber State Detection
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Solution Overview
Problem
Existing methods for determining whether a coated optical fiber is active or inactive at a downstream portion of a passive optical network (PON) are inadequate, particularly when a test light blocking filter is connected to an inactive fiber, and cannot distinguish between active and inactive fibers when the ONU has no power supply, especially at locations without a detachable connector.
Innovation Solution
A determination device and method that uses test light with multiple wavelengths to assess the reflectance ratios at the terminal end of the optical fiber, allowing for the identification of the fiber state, including whether an ONU with no power supply is connected, by analyzing the light intensity ratios or return losses at different wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test light blocking filter is connected to an inactive coated optical fiber, then the fiber appears to have reflection characteristics, but the existing methods cannot distinguish it from an active fiber with an ONU connected
Solution Approach 1:
The patent segments the measurement process into multiple wavelength components (1310nm and 1550nm), measuring reflectance at each wavelength separately. This segmentation allows the system to distinguish between different fiber states by analyzing the unique reflectance ratio patterns at different wavelengths, resolving the ambiguity caused by test light blocking filters.
Solution Approach 2:
The patent changes the measurement parameter from single-wavelength reflectance to multi-wavelength reflectance ratio. By measuring reflectance at multiple wavelengths and calculating their ratio, the system creates a new diagnostic parameter that uniquely identifies different fiber states, improving measurement precision without significantly increasing device complexity.
2Reliability
If the ONU has no power supply, then no uplink communication light is emitted, making it impossible to detect using existing methods
Solution Approach 1:
The patent performs preliminary measurement action by injecting test light from the OLT side before relying on any uplink signal from the ONU. This preliminary downlink test light measurement allows detection of fiber states regardless of ONU power status, ensuring reliable detection even when the ONU is unpowered.
Solution Approach 2:
Instead of detecting fiber states by receiving uplink light from the ONU (user end to network end), the patent inverts the approach by sending test light from the OLT (network end to user end) and measuring reflected light. This inversion allows detection without requiring ONU power or cooperation.
3Adaptability or versatility
If measurement is performed at locations without a detachable connector, then access to the fiber end is limited, but existing methods require connector access
Solution Approach 1:
The patent creates a universal measurement method that works through the existing PON downlink path, making the OLT itself a measurement device. This multi-functional approach allows fiber state detection through normal network operation paths, eliminating the need for special access points or detachable connectors at measurement locations.
Solution Approach 2:
The system uses its own downlink test light transmission path to perform the measurement, making the network infrastructure serve its own diagnostic needs. The OLT sends test light that naturally travels through the fiber being measured, and the reflected light returns through the same path, allowing self-service measurement without external access equipment.
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
Enables accurate determination of the fiber state, including whether an ONU with no power supply is connected, at any location where the coated optical fiber is exposed, without the need for a detachable connector, thereby improving the accuracy and flexibility of fiber identification.
Implementation Method 1
receive returned light generated by the test light in the optical fiber
Implementation Method 2
make test light having a plurality of wavelengths incident to the optical fiber
Data Source
AI summary
An object is to provide a determination device that determines a state of a terminal end portion of a coated optical fiber at any location of the coated optical fiber. Reflection of test light varies in a reflection amount at each wavelength depending on a situation of the terminal end portion of the coated optical fiber. In other words, if the magnitude of the reflection amount at each wavelength can be known, the situation of the terminal end portion of the coated optical fiber can be estimated. The determination device according to the present invention is configured to make test light having a plurality of wavelengths incident from the optical fiber side and determine the test light based on a light intensity ratio of each reflected light beams reflected at the terminal end. In addition, reflection of test light varies in return loss at each wavelength depending on a situation of the terminal end portion of the coated optical fiber. If Rayleigh backscattered light can also be measured when measuring a reflection amount, the return loss can be known for each wavelength, and the situation of the terminal end portion of the coated optical fiber can be estimated from the result. The determination device according to the present invention is configured to make test light having a plurality of wavelengths incident from the optical fiber side and determine the test light based on a return loss at the terminal end.