PON Access Fiber Testing Using Tunable Laser and AWG
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Solution Overview
Problem
Current methods for assessing the integrity of access fibers in passive optical networks (PONs) are inefficient and costly, particularly in detecting breaks or degradation, as they often focus more on the feeder fibers and struggle to accurately test the access fibers due to signal loss and accessibility issues.
Innovation Solution
The implementation of an OTDR system with a splitter module that includes an optical splitter, a cyclic AWG, and WDM couplers, utilizing a tunable laser to emit light of specific wavelengths greater than 1600 nm for testing access fibers, and a photo detector to capture and analyze reflections, all integrated on a PIC chip, allowing for reliable and cost-effective assessment of access fiber conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods are used to test access fibers, then the testing process is simple, but the measurement precision and reliability of detecting breaks or degradation is poor
Solution Approach 1:
The patent segments the fiber testing process by separating the feeder fiber testing from access fiber testing. It introduces a dedicated access fiber testing mode that isolates the access fiber segment from the feeder fiber, allowing independent testing of each segment. This segmentation enables precise detection of access fiber breaks without interference from feeder fiber conditions.
Solution Approach 2:
The patent uses an intermediary approach by introducing a test light source and detector system that acts as a mediator between the OTDR and the access fiber. The system sends test light through the feeder fiber to the optical splitter, then through the access fiber to the ONT, and detects reflections and transmissions. This intermediary testing mechanism enables precise measurement of access fiber integrity without requiring direct access to the fiber segments.
2Productivity
If feeder fiber testing is focused, then the testing process is efficient, but the access fiber integrity assessment becomes inaccurate
Solution Approach 1:
The patent implements dynamic testing capability by allowing the OTDR to switch between different testing modes - feeder fiber testing mode and access fiber testing mode. The system can dynamically adjust its operation to focus on different fiber segments based on the testing requirements, thereby maintaining high productivity while improving accuracy for specific fiber types.
Solution Approach 2:
The patent applies local quality by providing specialized testing parameters and methods for different fiber segments. The access fiber testing mode uses specific detection parameters optimized for access fiber characteristics, while the feeder fiber testing mode uses parameters optimized for feeder fiber. This localized optimization ensures that each fiber type is tested with appropriate precision.
3Measurement precision
If access fibers are made accessible for testing, then the measurement precision improves, but the device complexity and cost increase
Solution Approach 1:
The patent implements universality by designing the OTDR system to perform multiple functions - it can test both feeder fibers and access fibers using the same basic device. The system includes an optical splitter that can be configured to direct test light to different fiber segments, and the OTDR can operate in multiple testing modes. This multi-functionality reduces the need for separate specialized equipment for different fiber types.
4Reliability
If signal loss is reduced in the testing system, then the detection capability improves, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the optical splitter and test system before actual fiber testing. The optical splitter is positioned and connected in advance to establish optimal optical paths for testing access fibers. The test light source and detector are pre-aligned and calibrated. This preliminary setup minimizes signal loss during actual testing by ensuring the optical path is already optimized.
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 configuration enables more accurate and cost-effective testing of access fibers, reducing signal loss and improving detection capabilities compared to existing methods, allowing for timely and appropriate repairs in PONs.
Implementation Method 1
utilizing a tunable laser to emit light of specific wavelengths greater than 1600 nm for testing access fibers
Implementation Method 2
a photo detector to capture and analyze reflections
Implementation Method 3
an optical splitter, a cyclic AWG, and at least one WDM coupler for optically coupling an optical splitter communication link and a cyclic AWG communication link
Implementation Method 4
at least one WDM coupler for optically coupling an optical splitter communication link and a cyclic AWG communication link
Implementation Method 5
a cyclic AWG (arrayed waveguide grating)
Data Source
AI summary
A manner of providing for testing of access fibers in a PON (passive optical network) using OTDR (optical time-domain reflectometry). According to the invention, a PON includes an optical splitter module having one or more optical couplers that combines downstream light from 1×N optical splitter directing the output of an OLT (optical line terminal) and a cyclic AWG (arrayed waveguide grating) for transmission toward one or more ONUs (optical network units). The splitter module is preferably formed on a single semiconductor chip, such as a PIC (photonic integrated circuit) chip and may reside in an outside plant of the PON.