Symmetrical Supervisory Optical Circuit for Bidirectional Repeater Installation
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Solution Overview
Problem
Subsea network operators face challenges in optimizing the capacity and performance of fiber-optic cable plants to handle increasing bandwidth demands, requiring systems for fast fault detection, improved maintainability, and upgradable capacity while maintaining low-cost implementation and maintenance.
Innovation Solution
A bidirectional optical repeater with two unidirectional optical amplifiers and a symmetrical supervisory optical circuit that allows interchangeable optical input/output port pairs, enabling flexible installation orientations and reducing the risk and cost of installation errors, and utilizing narrow band-pass optical filters for effective supervisory signal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a directional orientation of optical repeaters is maintained throughout the cable system, then the supervisory optical circuit can function properly, but the installation process becomes more complex and error-prone
Solution Approach 1:
The patent applies asymmetry by introducing a directional asymmetry in the supervisory optical circuit through the use of unidirectional optical amplifiers and asymmetrical optical coupling. This allows the main signal to flow bidirectionally while the supervisory signal flows unidirectionally, enabling proper fault detection while maintaining installation flexibility.
Solution Approach 2:
The patent segments the optical circuit into separate signal paths: a main optical path for bidirectional data transmission and a supervisory optical path for unidirectional monitoring. This segmentation allows each path to be optimized independently, with the supervisory path using narrow band-pass filters and unidirectional amplifiers to ensure reliable fault detection without constraining installer orientation choices.
2Reliability
If conventional asymmetrical supervisory optical circuits are used, then fault detection can be achieved, but installation errors increase and cost increases
Solution Approach 1:
The patent makes the optical repeater universal by enabling it to function correctly regardless of installation orientation. The supervisory optical circuit uses unidirectional amplifiers and asymmetrical coupling that automatically adapt to the installation direction, allowing the same repeater design to be used in any orientation without requiring directional markings or specialized installation procedures.
Solution Approach 2:
The patent introduces narrow band-pass optical filters as intermediaries in the supervisory optical path. These filters selectively pass supervisory wavelengths while blocking other signals, enabling reliable fault detection through the unidirectional amplifiers without interfering with the bidirectional data transmission, thus achieving both fault detection and installation flexibility.
3Measurement precision
If narrow band-pass optical filters are used in the supervisory optical circuit, then supervisory signal management is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by placing narrow band-pass filters only in the supervisory optical path where precise wavelength selection is needed for fault detection, while leaving the main bidirectional data path unchanged. This localized application of filtering provides the necessary measurement precision for supervisory signals without adding complexity to the entire optical system.
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
The solution enhances the installation process, reduces installation errors, and supports efficient fault detection and maintenance, while ensuring flexible and cost-effective implementation of optical repeaters in subsea cable systems, thereby meeting the growing bandwidth demands.
Implementation Method 1
the first optical pathway including a first narrow band-pass optical filter and being configured to: direct light traveling in the first direction at the first optical input port toward the second optical output port, through the first narrow band-pass optical filter and through the second optical amplifier
Implementation Method 2
a first optical amplifier configured to amplify optical signals transmitted in a first direction
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the corresponding two optical paths through the repeater. In an example embodiment, the supervisory optical circuit is symmetrical in the sense that it enables the two optical input/output port pairs of the repeater to be interchangeable and functionally equivalent at least with respect to two supervisory wavelengths and some in-band and/or out-of-band wavelengths. This symmetry can advantageously be used, e.g., to improve the installation process directed at installing such optical repeaters in an undersea cable system. For example, a single directional orientation of the optical repeaters does not need to be maintained throughout the cable system, which can significantly reduce the risk and/or cost of installation errors.