Optical Receiver Power Optimization for WDM Noise
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Solution Overview
Problem
Conventional ROADM nodes lack sufficient flexibility to adapt to dynamic Internet-based traffic, leading to performance degradation due to optical signal to noise ratio (OSNR) penalties in filter-less architectures, where interference from multiple WDM channels affects the coherent receiver's ability to maintain optimal performance.
Innovation Solution
The implementation of an optical receiver system with a local oscillator and processor that maximizes the power level difference between the laser signal and WDM channels, adjusting the power levels to limit noise penalties and ensure optimal performance across varying numbers of channels, using a feedforward loop to calculate and control power levels based on saturation limits and noise considerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power level of the laser signal is increased to improve channel distinction in the mixer, then the signal-to-noise ratio improves, but the noise penalty increases due to interference from multiple WDM channels
Solution Approach 1:
The patent dynamically adjusts the power level parameter of the laser signal based on the detected number of WDM channels. The processor calculates the optimal power level that maximizes channel distinction while maintaining noise penalty below a threshold, thereby resolving the contradiction between measurement precision and harmful noise effects
Solution Approach 2:
The system implements a feedback mechanism where the processor continuously monitors the number of active WDM channels and adjusts the laser signal power level accordingly. This closed-loop control ensures that the power level is optimized in real-time to maintain channel distinction capability while limiting noise penalty accumulation
2Reliability
If the power level difference between the laser signal and WDM channels is maximized to improve signal detection, then the receiver sensitivity improves, but the system becomes more sensitive to noise and interference
Solution Approach 1:
The patent optimizes the power level difference parameter by calculating the maximum acceptable difference that maintains receiver sensitivity while keeping noise penalty below a threshold. This dynamic parameter adjustment resolves the contradiction between reliability and noise sensitivity
Solution Approach 2:
The system takes preliminary action by pre-calculating the optimal power level difference before signal reception, based on the expected number of WDM channels. This anticipatory adjustment prevents excessive noise sensitivity from developing in the first place
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 minimizes OSNR penalties within threshold levels, ensuring stable system performance by optimizing power differences between the local oscillator and WDM signals, thereby maintaining optimal operation regardless of the number of WDM channels, and reducing interference-related noise.
Implementation Method 1
the mixer is configured to receive signals on the plurality of channels and to utilize the laser signal to distinguish the signal on the selected channel
Data Source
AI summary
An optical receiver system is disclosed. The system includes a local oscillator, a mixer and a processor. The local oscillator is configured to generate a laser signal to indicate a selection of one of a plurality of channels. In addition, the mixer is configured to receive signals on the plurality of channels and to utilize the laser signal to distinguish the signal on the selected channel. Further, the processor is configured to maximize a power level difference between the laser signal and at least one of the plurality of channels based on a total number of the plurality of channels by adjusting the power of the laser signal input to the mixer to limit a noise penalty in the receiver system.