Coherent Signal Power Detection Without Wavelength Demultiplexer
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Solution Overview
Problem
In optical signal transmission, detecting the power of signals in wavelength division multiplexing systems using coherent reception methods is challenging due to the interference between optical signals and local oscillator signals, requiring innovative methods to accurately measure signal strength without an optical wavelength demultiplexer.
Innovation Solution
A signal detection method involving a frequency mixer that combines wavelength division multiplexing signals with a local oscillator signal of the same wavelength to produce a coherent signal, which is then amplified by a transimpedance amplifier and variable-gain amplifier, using a mapping function or table to determine the target signal's power based on feedback voltage signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent reception method is used to receive wavelength division multiplexing signals, then the signal detection capability is improved, but the difficulty of measuring signal power increases due to interference between optical signals and local oscillator signals
Solution Approach 1:
The patent segments the coherent signal into two paths: one path goes through the photodetector for power measurement, while the other path is discarded. This segmentation allows the system to measure signal power without being affected by the interference between optical signals and local oscillator signals, resolving the measurement difficulty while maintaining coherent reception capabilities
Solution Approach 2:
The patent extracts only the necessary component (signal power information) from the coherent signal by routing it through a photodetector, separating the measurement function from the coherent detection function. This extraction enables independent power measurement without requiring demultiplexing, solving the technical contradiction
2Adaptability or versatility
If optical wavelength demultiplexer is used to separate signals of different wavelengths, then the signal separation capability is improved, but the device complexity increases
Solution Approach 1:
The patent makes the frequency mixer serve multiple functions: it performs both coherent detection (by mixing optical signals with local oscillator) and signal separation (by generating electrical signals at different frequency offsets for different wavelengths). This multi-functionality eliminates the need for separate optical wavelength demultiplexers, reducing device complexity while maintaining signal separation capability
Solution Approach 2:
The patent replaces the optical wavelength demultiplexer (a complex optical component) with an electrical signal processing approach using frequency mixers and photodetectors. This substitution transitions from optical domain separation to electrical domain separation, simplifying the overall system structure
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 method allows for accurate extraction and measurement of target signal power without the need for an optical wavelength demultiplexer, enhancing the detection of optical signal power in wavelength division multiplexing systems and expanding application scope.
Implementation Method 1
performing, by a frequency mixer, interference on the wavelength division multiplexing signals through the local oscillator signal to obtain a coherent signal formed by the local oscillator signal and the target signal
Implementation Method 2
a coherent receiving manner of wavelength division multiplexing signals emerges. The approach is that, optical signals of different wavelengths, which are sent by a local laser set at a receiving end, imposes interference onto the signals of different wavelengths in the wavelength division multiplexing signals
Implementation Method 3
converting the coherent signal from an optical signal into an electric signal
Data Source
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AI summary
The present invention provides a signal detection method, including: receiving, by a frequency mixer, wavelength division multiplexing signals and a local oscillator signal, where a wavelength of the local oscillator signal and a wavelength of a target signal in the wavelength division multiplexing signals are the same; a frequency mixer performs interference on the wavelength division multiplexing signals through the local oscillator signal to obtain a coherent signal formed by the local oscillator signal and the target signal; sending the coherent signal to a transimpedance amplifier for amplification to obtain a voltage signal; and obtaining the power of the target signal according to a power amplitude of the voltage signal.