Coherent Optical Receiver Phase Modulation Frequency Offset
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Solution Overview
Problem
The complexity and high cost of implementing coherent receiving technology in optical communication systems due to the requirement for precise frequency offset control between the optical local oscillator and the optical signal, leading to significant optical power loss.
Innovation Solution
A signal processing method that generates a second optical signal with a 90-degree phase difference between its half periods, undergoes polarization splitting, frequency mixing, and optical-electrical conversion, allowing for correct coherent receiving even with arbitrary frequency offsets, thereby reducing system complexity and upgrade costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coherent receiving technology is used to improve sensitivity and power budget, then optical signal detection capability is improved, but device complexity and implementation cost increase due to precision frequency offset control requirements
Solution Approach 1:
The patent changes the working principle of the receiver from direct coherent detection to a method involving optical signal generation with controlled phase differences, polarization splitting, and frequency mixing. This parameter change in the detection mechanism eliminates the need for precision frequency offset control while maintaining sensitivity improvement, thereby resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent introduces an intermediary optical signal generated by a laser with controlled phase differences as a mediator between the incoming optical signal and the detection process. This intermediary signal enables coherent reception without requiring precise frequency matching, thus improving sensitivity without increasing device complexity
2Measurement precision
If precision control over frequency offset is implemented to achieve coherent receiving, then detection accuracy is improved, but optical power loss increases and system cost increases
Solution Approach 1:
The patent performs preliminary action by pre-controlling the phase difference of the generated optical signal to be 0, π/2, π, or 3π/2 relative to the incoming signal. This preliminary phase alignment eliminates the need for subsequent precision frequency offset control, maintaining detection accuracy while avoiding optical power loss and reduced system cost
3Reliability
If coherent receiving technology is deployed to improve power budget, then optical signal reception capability is improved, but implementation cost increases
Solution Approach 1:
The patent replaces expensive precision frequency control components with a cost-effective approach using standard lasers with controlled phase differences and polarization splitting components. This substitution maintains power budget improvement while significantly reducing implementation cost, making the system more manufacturable
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 coherent receiving with reduced complexity and optical power loss, eliminating the need for precise frequency offset control and allowing for improved sensitivity and power budget in optical communication systems.
Implementation Method 1
generating a second optical signal and modulating a phase of the second optical signal so that a difference between a phase of the second optical signal in the second half period and a phase of the second optical signal in the first half period is 90 degrees
Implementation Method 2
a polarization beam splitter, configured to perform polarization splitting separately on the first optical signal and the second optical signal
Implementation Method 3
the frequency mixer, configured to perform the frequency mixing processing on the polarization-split optical signals
Implementation Method 4
a first photodetector, configured to perform optical-electrical conversion after detecting the optical signals that have undergone the frequency mixing processing
Data Source
AI summary
A signal processing method, an optical receiver and optical network system is provided. The method includes: receiving a first optical signal sent by an optical network unit, generating a second optical signal and modulating a phase of the second optical signal, obtaining at least one path of electrical signals after the first optical signal and the second optical signal separately undergo polarization splitting, frequency mixing, and optical-electrical conversion, outputting a third electrical signal after performing operation processing on the at least one path of electrical signals, and restoring a data signal according to the third electrical signal and performing sending. The embodiments example benefits are greatly reducing complexity of system implementation and maximally reducing a system upgrade cost and an optical power loss.