Digital-Coherent Optical Receiver Bit Rate Adaptation
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Solution Overview
Problem
Existing optical communication systems face challenges in maintaining transmission performance as bit rates increase, leading to deterioration in signal quality due to OSNR ratio and waveform distortion, requiring expensive transmitters-receivers that can handle various bit rates.
Innovation Solution
A digital-coherent optical receiver with a sampling clock source and ADC circuits that adjust the parallel data signal's channel number based on bit rate, allowing the system to handle various bit rates without significant changes in sampling frequency or processing rate, and enabling flexible bit rate selection for optimal transmission capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bit rate per wavelength is increased to enhance transmission capacity, then the transmission capacity is improved, but the OSNR ratio significantly decreases resulting in signal quality deterioration
Solution Approach 1:
The patent changes the detection method from direct detection to coherent detection, which fundamentally alters how optical signals are processed. By using local oscillation light to mix with the signal light and detecting both amplitude and phase information, the system achieves much higher OSNR tolerance (20 dB or more) compared to direct detection, thereby maintaining signal quality at high bit rates
Solution Approach 2:
The patent replaces traditional direct detection mechanisms with coherent detection using photomixing. Instead of directly converting optical power to electrical signals, the system uses interference between signal light and local oscillation light in the photodetector, enabling extraction of phase information and achieving superior OSNR performance
2Reliability
If digital-coherent receiving methods are used to improve OSNR tolerance and waveform distortion compensation, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal coherent receiving system that can handle multiple bit rates (10 Gbit/s, 40 Gbit/s, 100 Gbit/s) and various modulation formats (QPSK, 16-QAM, 64-QAM) using the same hardware architecture. The system achieves multi-functionality through configurable ADC sampling rates and flexible digital signal processing, eliminating the need for separate receiving systems for different standards
Solution Approach 2:
The patent uses parameter changes in the ADC sampling rate to adapt to different bit rates. By adjusting the sampling rate (e.g., 2.5 GS/s for 10 Gbit/s, 10 GS/s for 40 Gbit/s, 25 GS/s for 100 Gbit/s) while maintaining the same coherent detection architecture, the system achieves versatile operation without increasing fundamental device complexity
3Adaptability or versatility
If transmitters-receivers are designed to handle various bit rates, then adaptability is improved, but cost increases
Solution Approach 1:
The patent designs a universal optical receiver that can operate at multiple bit rates (10, 40, 100 Gbit/s) and support various modulation formats using the same hardware platform. The system uses configurable ADC sampling rates and flexible digital signal processing to achieve multi-functionality, thereby reducing the need for multiple specialized receivers and lowering overall system cost
Solution Approach 2:
The patent implements dynamic adaptability by allowing the receiver to adjust its operating parameters (sampling rate, processing configuration) based on the input signal characteristics. This dynamic operation enables a single receiver to adapt to different bit rates and modulation formats, providing cost-effective versatility
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
Enables efficient handling of multiple bit rates without the need for frequent changes in sampling frequency or processing rate, reducing costs and improving transmission capacity and flexibility in optical communication networks.
Implementation Method 1
a photo-detector that converts a received optical signal into an electric signal
Data Source
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AI summary
An optical receiver includes a photo-detector that converts a received optical signal into an electric signal and outputs the electric signal, a converter that converts the electric signal into a parallel data signal and outputs the parallel data signal, and parallel-number changer changing a parallel number of the parallel data signal in accordance with a bit rate of the optical signal and outputting the parallel data signal having the changed parallel number.