Wavelength Locking via Phase Discrimination
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Solution Overview
Problem
Current wavelength locking and controlling methods in DWDM systems require significant hardware and software resources, especially as the number of wavelengths increases, due to the need for unique scrambling frequencies and precise ADC accuracy, leading to increased complexity and cost.
Innovation Solution
Injecting scrambling signals with the same frequency but different phases into wavelength channels, allowing for optical splitting and phase discrimination to determine wavelength shifts, which are then used to adjust the wavelengths, thereby reducing the complexity of the control circuit and resource requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional scrambling is performed on each laser respectively with unique scrambling frequencies, then wavelength locking and controlling can be achieved, but the area of PCB and the complexity of control circuit are increased significantly
Solution Approach 1:
The patent merges the scrambling functions for multiple lasers into a single control circuit. Instead of having separate scrambling circuits for each laser wavelength, one scrambling circuit generates scrambled signals that are distributed to control multiple lasers simultaneously, thereby reducing PCB area and control circuit complexity while maintaining wavelength locking accuracy
Solution Approach 2:
The patent makes a single scrambling circuit universal by enabling it to control multiple laser wavelengths through time-division or frequency-division multiplexing. The same scrambling circuit is reused across different time slots or frequency channels to scramble signals for multiple lasers, eliminating the need for dedicated scrambling circuits for each wavelength
2Measurement precision
If multi-channel scrambling is performed with unique scrambling frequencies for each wave, then wavelength discrimination can be achieved, but required hardware and software resources are increased dramatically
Solution Approach 1:
The patent combines multiple wavelength discrimination functions into a single FFT processing unit. Instead of having separate processing chains for each wavelength channel, one FFT unit processes combined signals from multiple channels by exploiting time-division or frequency-division multiplexing patterns, thereby dramatically reducing hardware and software resource requirements
Solution Approach 2:
The patent employs periodic action by using time-division multiplexing where each wavelength channel is scrambled with the same base frequency but at different time slots or periodic intervals. This periodic structure allows a single FFT processor to distinguish between wavelengths by detecting the periodic patterns corresponding to each channel, reducing resource requirements while maintaining discrimination accuracy
3Reliability
If each wave is added with a unique scrambling frequency, then wavelength locking can be achieved, but critical resources such as Digital/Analog lane number and micro-processing capability are challenged
Solution Approach 1:
The patent makes a single micro-processor and DA lane universal by enabling it to handle multiple wavelength channels through time-division or frequency-division multiplexing. The same processor generates scrambled signals for multiple lasers sequentially or the same DA lane outputs scrambled signals that are distributed to multiple channels, reducing the number of critical resources needed while maintaining locking stability
Solution Approach 2:
The patent uses periodic action where a single scrambling signal generator produces signals at regular intervals that are distributed to multiple wavelength channels. This periodic generation approach allows one micro-processor to control multiple lasers by timing the signal generation appropriately, reducing processing capability requirements while ensuring reliable wavelength locking for all channels
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 allows for efficient adjustment of multiple wavelengths with reduced hardware and software needs, saving cost and PCB area while maintaining accurate wavelength control.
Implementation Method 1
optically splitting and wavelength locking the modulated signals to acquire PD signals
Data Source
AI summary
A wavelength locking method, apparatus, and system are provided. The wavelength locking method includes modulating, by using scrambling signals with a same frequency and different phases, each one of a plurality of optical channel signals respectively; processing, by a combiner, a splitter, and a wavelength locker, the modulated optical signals, so as to acquire photoelectricity detector (PD) signals; performing phase discrimination on the PD signals to acquire wavelength information of the optical channels; determining different shift values corresponding to the different wavelength information; and adjusting wavelengths of the optical channels according to the corresponding shift values.