Coherent Optical Receiver Signal Splitting for Frequency Offset Suppression
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Solution Overview
Problem
Current coherent optical communication systems face challenges with frequency offsets and phase noise due to the difficulty in maintaining identical frequencies between the local oscillator and received optical signals, leading to low bandwidth efficiency and high manufacturing costs, especially when using separate optical sources and fibers.
Innovation Solution
A receiver device that splits the received optical signal into two paths, amplifies one path to ensure the output is within the saturation region of a second amplifier, and uses the amplified signal as a local oscillator for coherent detection, eliminating the need for additional optical sources or fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate optical sources are used for the local oscillator and received signal, then frequency stability can be maintained, but frequency offsets occur due to environmental factors and manufacturing variations
Solution Approach 1:
The patent merges the local oscillator signal and received signal into a single optical path, using a single optical source that is split by an optical coupler. This eliminates frequency offsets between separate sources while maintaining stability through unified source control.
Solution Approach 2:
The patent segments the optical signal into multiple paths using an optical coupler, dividing the single optical source output into separate local oscillator and received signal paths. This allows independent processing of each path while maintaining frequency coherence through common source origin.
2Reliability
If additional optical fibers are installed to transmit the local oscillator signal, then frequency control is improved, but system complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the transmission of local oscillator and received signal into a single optical fiber path by using an optical coupler to split and recombine signals. This eliminates the need for separate optical fibers while maintaining frequency control through the unified optical path.
Solution Approach 2:
The single optical fiber serves multiple functions by carrying both the local oscillator signal and received signal through the same medium. The optical coupler enables this multi-functionality by directing different signal portions through the shared fiber infrastructure.
3Manufacturing precision
If the amplifier operates in linear region, then signal distortion is minimized, but the output signal does not reach the saturation region required for optimal coherent detection
Solution Approach 1:
The patent dynamically adjusts the amplifier operating region based on signal requirements. The amplifier operates in different regions (linear and saturation) depending on which signal path requires amplification, optimizing performance for each specific function rather than maintaining a fixed operating point.
Solution Approach 2:
The patent changes the operating parameters of the amplifier by controlling which signal path receives amplification. By selectively amplifying either the local oscillator or received signal path, the system adapts the amplifier's operating characteristics to match the specific detection requirements.
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 suppresses frequency offsets and minimizes phase noise while reducing manufacturing costs by utilizing existing optical signals within the coherent optical communication system, enhancing bandwidth efficiency without additional optical sources or fibers.
Implementation Method 1
an optical splitter configured to split a received optical signal into at least two paths
Implementation Method 2
a first amplifier configured to amplify a second optical signal from among a first optical signal and the second optical signal split into two paths
Implementation Method 3
a coherent receiver module configured to mix the output signal of the second amplifier and the first optical signal and perform detection on the mixed signal
Data Source
AI summary
A receiver device and receiving method for a coherent optical communication system are disclosed. The disclosed device includes: an optical splitter configured to split a received optical signal into at least two paths; a first amplifier configured to amplify a second optical signal from among a first optical signal and the second optical signal split into two paths; a second amplifier configured to amplify the output signal of the first amplifier; and a coherent receiver module configured to mix and detect the output signal of the second amplifier and the first optical signal. The disclosed device provides the advantages of suppressing the occurrence of frequency offsets and minimizing phase noise, as well as allowing manufacture with a low cost without requiring either an additional optical source or additional optical fibers.