Multi-Core Optical Fiber with Varied Mode-Dependent Loss for Tapping Detection
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Solution Overview
Problem
Optical communications systems face challenges in detecting eavesdropping attempts, as eavesdroppers can tap information from optical fibers without being easily detected, compromising confidentiality.
Innovation Solution
A multi-core optical fiber with distinct mode-dependent loss (MDL) characteristics in different core regions, where the first MDL is at least 50% greater than the second MDL at a given bend radius, allowing for detection of signal tapping by calculating a figure of merit (FOM) based on received power changes exceeding a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fiber transmission is used for data communication, then robustness to interception is improved, but detectability of eavesdropping attempts deteriorates
Solution Approach 1:
The patent applies local quality by creating different MDL characteristics in different core regions of the optical fiber. Specifically, the first core region has a first MDL FOM with a first bend-radius dependence, while the second core region has a second MDL FOM with a second bend-radius dependence, where the first MDL FOM is at least about 50% greater than the second MDL FOM at a given bend radius. This spatial differentiation allows the system to detect eavesdropping attempts by monitoring changes in the FOM of individual cores.
Solution Approach 2:
The patent implements feedback by continuously monitoring the FOM of transmitted optical signals and comparing it against expected values. The system calculates the FOM based on received power measurements and determines when a change exceeds a predetermined threshold, which triggers an alert for potential eavesdropping. This closed-loop feedback mechanism enables real-time detection of security compromises.
2Difficulty of detecting and measuring
If multi-core optical fiber with varied MDL is used, then eavesdropping detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the optical fiber into multiple core regions, each with distinct MDL characteristics. The fiber includes a cladding region with a plurality of optical cores, where at least a first core region and a second core region have different MDL FOMs. This segmentation allows independent characterization and monitoring of each core's security status.
Solution Approach 2:
The patent utilizes parameter changes by varying the MDL FOM across different core regions through differences in core medium, waveguide design, or cladding effective refractive index. These parameter variations create distinguishable FOM signatures that enable detection of eavesdropping attempts while maintaining a manageable fiber structure.
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 reliable detection of eavesdropping attempts by differentiating between legitimate bending and eavesdropping-induced power changes, enhancing the security of optical communication systems by increasing secrecy capacity.
Implementation Method 1
A first core region of the plurality has first mode-dependent loss (MDL) figure of merit (FOM) with a first bend-radius dependence. A second core region of the plurality has a second MDL FOM with a second bend-radius dependence.
Implementation Method 2
receiving first and second optical signals via respective first and second optical cores of a multi-core optical fiber
Data Source
AI summary
Various embodiments provide for detection of tapping of an optical signal. In one embodiment an optical fiber includes a cladding region and first and second core regions. The first core region has a first core medium having a first mode-dependent loss (MDL) figure of merit. The second core region has a second core medium having a second different MDL figure of merit. Tapping of the optical signal may be determined to occur when the MDL of the first and second optical signals differs by a predetermined threshold value.