Optical Add-Drop Device Phase Shifter Feedback Control
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Solution Overview
Problem
The center wavelength offset in wavelength filters of conventional optical add-drop devices due to production errors and temperature dependence leads to signal loss and crosstalk in wavelength division multiplexing systems, degrading signal quality.
Innovation Solution
The optical add-drop device incorporates multiple sub optical circuits with phase shifters and couplers, allowing for adjustable path length differences to align wavelengths accurately, reducing signal loss and crosstalk through feedback control and monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an accurate manufacturing process is used to reduce center wavelength offset, then signal quality is improved, but production cost increases
Solution Approach 1:
The patent implements a feedback control mechanism where the controller measures the actual center wavelengths of the wavelength filters and adjusts the path length differences in the optical circuits to compensate for deviations. This closed-loop system eliminates the need for highly precise manufacturing by allowing post-manufacturing calibration, thereby resolving the contradiction between manufacturing precision and production cost.
Solution Approach 2:
The patent changes the path length difference parameter in the optical circuits dynamically to compensate for manufacturing errors in filter center wavelengths. By adjusting this physical parameter through the controller, the system can achieve accurate wavelength alignment without requiring precise manufacturing, thus reducing production costs while maintaining signal quality.
2Reliability
If the center frequency of the wavelength filter is offset from the target wavelength, then signal loss and crosstalk increase, but using accurate manufacturing processes increases production cost
Solution Approach 1:
The controller uses feedback from wavelength measurements to adjust the path length differences, ensuring that the system maintains high signal quality despite manufacturing variations. This feedback mechanism allows the system to compensate for filter center frequency offsets, preventing signal loss and crosstalk without requiring expensive accurate manufacturing processes.
Solution Approach 2:
The system performs preliminary calibration by measuring the actual center wavelengths of the filters and pre-adjusting the path length differences before normal operation. This preliminary action ensures that the system is properly configured to handle manufacturing variations, maintaining reliability while avoiding the need for costly precision manufacturing.
3Reliability
If the center frequency of the wavelength filter is offset from the target wavelength, then crosstalk between wavelength channels occurs, but using accurate manufacturing processes increases production cost
Solution Approach 1:
The controller adjusts the path length difference parameter to compensate for filter center frequency offsets, ensuring proper wavelength channel isolation. By dynamically changing this parameter based on measured wavelengths, the system prevents crosstalk between channels without requiring expensive precision manufacturing processes.
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 configuration effectively reduces signal loss and crosstalk, maintaining signal quality without the need for precise manufacturing processes, thereby lowering production costs and ensuring performance across varying temperatures.
Implementation Method 1
Each of the one or more optical circuits includes a first sub optical circuit, a second sub optical circuit, and a third sub optical circuit. Each of the first sub optical circuit, the second sub optical circuit and the third sub optical circuit includes an input coupler, an output coupler, and a phase shifter implemented between the input coupler and the output coupler.
Implementation Method 2
The DBR depicted in FIG. 1, which is an example of a wavelength filter, reflects light of wavelength λi and transmits other frequency components.
Data Source
AI summary
An optical add-drop device includes optical circuits. Each of the optical circuits includes first to third sub optical circuits. Each sub optical circuit includes an input coupler, output coupler, and a phase shifter. In each of the optical circuit, two ports of the output coupler in the first sub optical circuit are respectively coupled to the input coupler in the second sub optical circuit and the input coupler in the third sub optical circuit. The output coupler in the second sub optical circuit in each of the optical circuits is coupled to a drop port or the input coupler in the first sub optical circuit in the adjacent optical circuit. The input coupler in the third sub optical circuit in each of the optical circuits is coupled to an add port or the output coupler in the third sub optical circuit in the adjacent optical circuit.