Redundant Optical Source Switching for Fibre Amplifier SBS Protection
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Solution Overview
Problem
High power fibre amplifiers in laser systems are vulnerable to catastrophic damage from stimulated Brillouin scattering (SBS) due to insufficient spectral broadening, which can occur rapidly and affect multiple components, including the seed laser.
Innovation Solution
An optical source with a primary and secondary channel, each equipped with a seed laser and spectral broadening apparatus, coupled by an optical combiner and monitored by optical monitoring apparatus, allows for fast switching between channels via fast optical switches (SOAs) to prevent SBS by ensuring adequate spectral broadening, using optical delay lines and control circuitry to manage fault detection and reconfiguration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spectral broadening module is used to broaden seed laser signal, then stimulated Brillouin scattering (SBS) is mitigated in fibre amplifier, but the fibre amplifier becomes vulnerable to catastrophic damage if the spectral broadening module fails
Solution Approach 1:
The patent implements a monitoring system that continuously checks the spectral broadening module operation before damage can occur. Fast optical switches are pre-positioned to immediately redirect the seed laser signal away from the fibre amplifier if broadening failure is detected, preventing catastrophic damage before it happens.
Solution Approach 2:
The patent introduces an intermediary monitoring system between the spectral broadening module and the fibre amplifier. This intermediary detects broadening failures and activates fast optical switches to isolate the fibre amplifier from unbroadened seed signals, preventing direct damage while maintaining system functionality.
2Productivity
If fast optical switches are implemented for channel switching, then continuous operation is enabled during faults, but device complexity increases
Solution Approach 1:
The patent divides the optical source into multiple independent channels, each with its own seed laser and spectral broadening module. Fast optical switches are assigned to each channel to independently control signal routing. This segmentation allows one channel to fail while another continues operation, maintaining productivity despite increased component count.
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 provides protection for the optical fibre amplifier, ensuring continuous operation by preventing SBS and enabling high power output, even in the event of spectral broadening module failures.
Implementation Method 1
spectral broadening apparatus for broadening the seed laser signal to provide a broadened laser signal having a second spectral linewidth, broader than the seed spectral linewidth
Implementation Method 2
optical fibre amplifier for amplifying the broadened laser signal
Implementation Method 3
first fast optical switch and a second fast optical switch. The control circuitry is configured to output at least one switching control signal to cause the first fast optical switch to be configured to block optical signals and to cause the second fast optical switch to be configured to pass optical signals
Implementation Method 4
optical monitoring apparatus configured to receive the first optical tap signal and output a first alarm signal responsive to determining that the first optical tap signal is indicative of a fault in the spectral broadening apparatus
Implementation Method 5
the resulting pulsing due to SBS can cause catastrophic damage to the fibre amplifier in a very short time. The SBS also produces backward travelling pulses which can damage many components of a laser system
Data Source
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Figure 1A
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AI summary
An optical source (100) comprising a primary optical signal source (110), a first optical tap (102) for forming an optical tap signal, a first fast optical switch (104), a secondary optical signal source (120) and a second fast optical switch (106). Each optical signal source comprises a seed laser (112, 122) for generating a seed laser signal and spectral broadening apparatus (114, 124) to broaden the seed laser signal to output a broadened laser signal. The optical source further comprises an optical fibre amplifier (108), an optical combiner (128), optical monitoring apparatus (118) and control circuitry (126). The optical monitoring apparatus is configured to output an alarm signal responsive to determining that the optical tap signal is indicative of a fault in the spectral broadening apparatus of the primary optical signal source resulting in insufficient broadening of the seed laser signal. The control circuitry (126) is configured to output: an initial control signal to cause the first fast optical switch to pass optical signals and the second fast optical switch to block optical signals; and a switching control signal, responsive to receiving the first alarm signal, to cause the first fast optical switch to block optical signals and to cause the second fast optical switch to pass optical signals.