Incoherent Optical Frequency Domain Reflectometry for Fibre Break Detection
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Solution Overview
Problem
Current methods for detecting and locating fibre breaks in optical networks are either disruptive to traffic, require expensive additional equipment, or involve manual labor, making them inefficient and costly.
Innovation Solution
The use of incoherent optical frequency domain reflectometry (IOFDR) to modulate an optical signal with a test signal at the same wavelength as the traffic signal, allowing for the detection of fibre breaks without disrupting traffic and using existing amplification equipment, enabling precise location of breaks within the fibre.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OTDR methods are used to detect fibre breaks, then the position of breaks can be determined, but traffic on the fibre is disrupted and downstream receiver optics may be damaged
Solution Approach 1:
The patent uses an optical amplifier as an intermediary device that converts high-power pump laser radiation into low-power signal radiation at the transmitter wavelength. This mediator allows the fibre to be probed with high power for break detection while the actual traffic signal experiences only low power, avoiding disruption and damage to downstream optics
Solution Approach 2:
The patent changes the power parameter of the probe signal by using optical amplification. The pump laser operates at high power to enable sensitive break detection, while the optical amplifier converts this to low-power signal radiation that coexists with traffic signals without causing disruption or damage
2Measurement precision
If in-band OTDR signals are used, then break detection is achieved, but traffic is severely disrupted and equipment may be damaged
Solution Approach 1:
The optical amplifier serves as a mediator that decouples the power levels of the probe signal and the traffic signal. It allows in-band operation where both signals share the same wavelength, while maintaining different power levels through the amplification process - high power for pumping, low power for traffic
Solution Approach 2:
The system uses feedback by monitoring the backscattered light from the fibre and comparing it with the transmitted pump signal to detect breaks. The optical amplifier continuously provides the necessary gain to maintain signal levels while the system monitors for changes indicating fibre breaks
3Measurement precision
If out-of-service testing is performed, then accurate break detection is possible, but labour costs and downtime increase
Solution Approach 1:
The patent enables continuous operation by allowing the fibre to remain in service during break detection. The optical amplifier allows the probe signal and traffic signal to coexist at different power levels, eliminating the need to take the fibre out of service for testing
Solution Approach 2:
The system performs preliminary break detection continuously or periodically while the fibre is operational. The optical amplifier is already in place for signal transmission, so no additional out-of-service setup is required - the detection capability is prepared in advance and can be activated immediately
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 precise detection and location of fibre breaks without disrupting traffic or risking damage to downstream optics, reducing labour costs and equipment expenses, and functioning for both in-service and out-of-service systems.
Implementation Method 1
an optical amplifier which is adapted to convert high power pump laser radiation into low power signal radiation at a transmitter wavelength
Implementation Method 2
a modulator which is adapted to modulate the low power signal radiation with the probe signal
Implementation Method 3
the modulated low power signal radiation is transmitted to a far end of the optical fibre
Implementation Method 4
probing the optical fibre for breaks using a probe signal at the transmitter wavelength
Data Source
AI summary
A method of monitoring (200) an optical fiber comprises modulating (210) an optical signal with a traffic signal; modulating (220) the optical signal with an incoherent optical frequency domain reflectometry, IOFDR, test signal; transmitting (230) the doubly modulated optical signal onto an optical fiber at a first end of the fiber; detecting (240) scattered radiation output from the first end of the fiber; and analyzing (250) the detected scattered radiation using incoherent optical frequency domain reflectometry to determine a distance to a break in the optical fiber. Apparatus suitable for carrying out the method is also described, as well as an optical communications network employing the method.