Optical Transceiver APC Mode Switching for OTDR Testing
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Solution Overview
Problem
Automatic power control in passive optical networks can weaken or submerge OTDR test signals during maintenance, preventing normal testing and fault location.
Innovation Solution
Implementing seamless switching between open-loop and closed-loop modes of the automatic power control loop in the optical transceiver module to maintain a constant bias current during OTDR tests, ensuring the integrity of the OTDR test signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If automatic power control adjusts bias current based on output optical power monitoring, then optical power stability is improved, but OTDR test signal intensity deteriorates
Solution Approach 1:
The system dynamically switches between closed-loop automatic power control mode and open-loop test mode based on whether an OTDR test is being performed. During normal operation, the APC loop maintains stable optical power by adjusting bias current. During OTDR testing, the system transitions to open-loop mode to preserve test signal intensity, resolving the contradiction between power stability and test signal strength.
Solution Approach 2:
The invention changes the control parameter state by disabling the automatic power control loop during OTDR tests. This parameter change (from active control to passive hold) prevents the APC mechanism from reducing bias current in response to power fluctuations caused by superimposed test signals, thereby maintaining adequate test signal intensity while still providing optical power stability during normal operation.
2Adaptability or versatility
If OTDR test signal is superimposed to communication data, then network maintenance capability is improved, but optical power fluctuation increases
Solution Approach 1:
The invention introduces a test control signal as an intermediary that mediates between the OTDR testing function and the automatic power control system. This control signal enables the system to distinguish between normal communication data and test signals, allowing the APC loop to be selectively disabled only during testing when superimposition occurs, thus managing both maintenance capability and power stability.
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 prevents the weakening or submersion of OTDR test signals, allowing for effective testing and fault location by maintaining the bias current at a preset target value during the test period.
Implementation Method 1
adjusting a bias current of the optical source according to a power monitoring result, thereby implementing automatic power control
Data Source
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AI summary
The present application provides a method for controlling optical power, the method includes: monitoring output optical power of an optical source, and judging whether a preset test control signal is received; when the preset test control signal is not received, modulating a data signal to output light of the optical source, and adjusting a bias current of the optical source according to an output optical power monitoring result of the optical source to implement automatic power control; and when the preset test control signal is received, starting a test and superimposing a test signal to the data signal to form a superimposed signal and modulating the superimposed signal to the output light of the optical source, the output optical power monitoring result of the optical source is ignored during the test period to maintain the bias current of the optical source at a preset target value. The present application further provides an apparatus for controlling optical power.