Optical Fiber Type Identification via Chromatic Dispersion Analysis
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Solution Overview
Problem
Current methods for identifying optical fiber types in networks are either hardware-intensive or unreliable, lacking cost-effective solutions that do not require additional equipment, which is essential for optimizing fiber communications and evaluating nonlinear interference.
Innovation Solution
The method involves applying varying pre-dispersion values to a signal and measuring the bit error rate to map local minimums, determining the span dispersion, and using the accumulated dispersion and span length to identify fiber types, which can be done using existing or additional hardware, including a transmitter, receiver, and processor, with optional optical time domain reflectometry for span length determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If online fiber type detection based on chromatic dispersion coefficient is used, then fiber type identification capability is improved, but additional hardware is required
Solution Approach 1:
The existing coherent transceiver in the optical network is made to perform fiber type identification functions by analyzing total light path dispersion data that it already collects during normal operation. The transceiver uses its existing dispersion compensation and measurement capabilities to identify fiber types without requiring separate dedicated hardware, making the system self-sufficient for this identification task.
Solution Approach 2:
The coherent transceiver is designed to perform multiple functions: standard optical signal transmission and reception, dispersion compensation, and now fiber type identification. By integrating fiber type identification into the transceiver's existing dispersion analysis functionality, the system achieves multi-functionality without adding specialized hardware dedicated solely to fiber identification.
2Device complexity
If algorithm-based fiber type identification using total light path dispersion is used, then hardware requirements are reduced, but reliability is insufficient
Solution Approach 1:
The total light path dispersion is segmented into individual span dispersions by identifying local minimums in the bit error rate curve that correspond to amplifier locations. Each span's dispersion contribution is calculated separately, and these individual span dispersions are then used to determine fiber types for specific fiber segments, providing more granular and reliable identification compared to analyzing only the total accumulated dispersion.
Solution Approach 2:
The system uses bit error rate measurements as feedback to identify local minimums that mark amplifier positions. This feedback mechanism allows the algorithm to automatically locate span boundaries and extract accurate span-specific dispersion values, improving the reliability of fiber type identification by using actual system performance data rather than relying solely on theoretical total dispersion calculations.
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 allows for reliable identification of fiber types without additional specialized equipment, facilitating quality control and accurate evaluation of fiber and signal properties, such as nonlinear interference, enabling proper installation of equipment like distributed Raman amplifiers.
Implementation Method 1
A link between a transmitter and a receiver can contain one or more spans of different optical fibers... By applying a range of different pre-dispersions (preCD) to a signal... The difference in accumulated dispersions (CD) at two extremities of a span can be used with the corresponding length of the span, to obtain a coefficient of dispersion (D)
Data Source
AI summary
A method to determine the types of optical fibers forming a link of an optical communication network. By scanning a signal's bit error rate at a receiver end, as a function of a pre-dispersion applied to a signal at a transmitter end, local minimums in the curve indicate the presence of amplifiers, and therefore fiber span extremities. By determining the accumulated dispersion at each fiber extremity, a ratio of dispersion per span length can be obtained and the span's coefficient of chromatic dispersion be inferred, thereby identifying the type of fiber. Alternatively, a signal's signal-to-noise ratio can be scanned, instead of its bit error rate. In a typical network, the required instrumentation is pre-existing.