Optical Network Unit Wavelength Tracking for Coherent PON Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coherent passive optical networks face challenges in receiving uplink burst-mode signals due to limited bandwidth of balanced photodetectors, leading to out-of-band frequency tracking issues, where signals from some optical network units (ONUs) cannot be detected by the optical line terminal (OLT) due to wavelength variations beyond the detection range.
Innovation Solution
A wavelength tracking mechanism is implemented, where the OLT configures the laser chip temperature of the ONU to adjust its emission wavelength, using temperature adjustment information and a wavelength tracking table to track the wavelength and corresponding temperature, and a specially designed registration signal is used for new ONUs to access the OLT, ensuring signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent detection is used to improve receiving sensitivity, then receiving sensitivity is improved, but the cost of coherent transceivers increases and detection difficulty arises
Solution Approach 1:
The patent changes the wavelength parameter of the optical signal by adjusting the laser chip temperature. The OLT sends temperature adjustment information to the ONU, which then adjusts its laser emission wavelength to match the OLT's local oscillator wavelength, enabling coherent detection without requiring complex transceiver designs
Solution Approach 2:
The patent implements a feedback mechanism where the OLT detects the wavelength of incoming signals from multiple ONUs, determines the optimal wavelength for coherent detection, and sends temperature adjustment information back to the ONUs. This closed-loop feedback enables wavelength synchronization and successful coherent detection
2Measurement precision
If wavelength tracking is implemented to adjust emission wavelength, then signal detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical wavelength tuning mechanisms with a thermal control system. By adjusting the temperature of the laser chip, the emission wavelength is tuned to match the OLT's local oscillator wavelength, simplifying the wavelength tracking mechanism while maintaining detection accuracy
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 solution effectively addresses the out-of-band frequency tracking problem by adjusting the ONU's wavelength to be within the detection range of the OLT, ensuring successful signal reception and improving the overall efficiency of coherent PON systems.
Implementation Method 1
based on the temperature adjustment information, the emission wavelength of the laser is adjusted by adjusting the temperature of the laser chip
Data Source
Figure 1A
Figure 1B(a)~1B(b)
Figure 1C(a)~1C(b)
AI summary
Embodiments of the present disclosure relate to optical network units, optical line terminals, and methods, devices, and media for communication. An optical network unit is configured to send a plurality of optical signals with different wavelengths to an optical line terminal. The optical signals in the plurality of optical signals carry indicating information. The indicating information is used to indicate the wavelength serial number of the optical signal and the temperature information of the laser chip when the optical signal is generated; Receiving temperature adjustment information from the optical line terminal; And based on the temperature adjustment information, the emission wavelength of the laser is adjusted by adjusting the temperature of the laser chip. In this way, a new kind of registered optical signal of optical network unit is provided, at least to solve the problem that the optical line terminal cannot detect the signal in the upstream burst mode coherent detection.