Light Receiving Device Phase Adjustment for Chromatic Dispersion
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Solution Overview
Problem
Digital coherent receiving methods have a low tolerance to waveform distortion caused by chromatic dispersion and polarization mode dispersion, particularly due to fluctuations in polarization conditions, which degrades signal quality in high-bit-rate optical transmission systems.
Innovation Solution
A light receiving device and method that includes multiple fixed distortion compensators and phase shift detector circuits to detect and adjust the sampling phase shift, using a phase-adjusting-amount determiner to reduce phase differences between the sampling clock and the received optical signal, thereby enhancing tolerance to waveform distortion and polarization mode dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital coherent receiving method is used to improve OSNR tolerance, then signal quality improves, but tolerance to waveform distortion caused by chromatic dispersion and polarization mode dispersion deteriorates
Solution Approach 1:
The patent divides the distortion compensation function into multiple fixed distortion compensators with different fixed compensation amounts. Instead of using a single compensator, the system segments the compensation task across multiple parallel paths, each handling a specific distortion level, thereby improving tolerance to waveform distortion while maintaining OSNR tolerance benefits
Solution Approach 2:
The patent introduces dynamic selection and switching mechanisms that allow the system to adaptively choose the appropriate distortion compensation amount based on actual transmission conditions. This dynamic adaptation enables the system to maintain high tolerance to waveform distortion despite using fixed compensation amounts in individual compensators
2Measurement precision
If sampling phase shift detector circuit is used for phase detection, then phase information can be extracted, but tolerance to waveform distortion fluctuation deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the output of phase shift detector circuits is fed back to adjust the distortion compensation amounts. This feedback loop allows the system to continuously optimize phase detection accuracy while compensating for waveform distortion fluctuations, thereby maintaining high tolerance to polarization mode dispersion
Solution Approach 2:
The patent introduces intermediary distortion compensation stages between the photoelectric conversion and phase detection. These intermediary compensators act as mediators that pre-condition the signal to reduce waveform distortion before it reaches the phase shift detector, thereby improving the detector's tolerance to polarization mode dispersion while maintaining phase 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
The solution significantly improves the tolerance to waveform distortion and polarization mode dispersion, ensuring stable signal quality and accurate phase adjustment, even in the presence of large waveform distortions, by using multiple fixed distortion compensators and phase shift detectors to compensate for chromatic dispersion and polarization mode effects.
Implementation Method 1
an analog signal being obtained through a photoelectric conversion of a received optical signal
Data Source
AI summary
A light receiving device includes: a converter digitalizing an analog signal with a given sampling clock frequency, the analog signal being obtained through a photoelectric conversion of a received optical signal; a plurality of fixed distortion compensators compensating an output signal of the converter for waveform distortion with a fixed compensation amount that is different from each other; a plurality of phase shift detector circuits detecting a sampling phase shift from an output signal of the plurality of the fixed distortion compensators; a phase-adjusting-amount determiner determining a sampling phase adjusting amount with use of an output signal of the plurality of the phase shift detector circuits; and a phase adjusting circuit reducing a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the phase-adjusting-amount determiner.