Optical Transmission Wavelength Spacing Control
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Solution Overview
Problem
Current optical transmission systems face challenges in efficiently managing wavelength spacing in super-channel technology, leading to reduced spectral efficiency and increased transmission degradation due to fluctuations in emission wavelengths, which affects channel spacing and overall network capacity.
Innovation Solution
The implementation of a system that includes a monitor transponder to perform digital coherent reception and transform signals into frequency domain spectra, allowing for real-time monitoring of wavelength spacing and adaptive wavelength control, enabling precise adjustment of transmission wavelengths to maintain optimal channel spacing and reduce transmission errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wavelength spacing is reduced to increase network capacity, then spectral efficiency is improved, but transmission degradation increases due to wavelength fluctuations
Solution Approach 1:
The patent implements a feedback mechanism where the receiver measures wavelength spacing of received optical signals and feeds back this information to the transmitter. The transmitter then adjusts its wavelength spacing based on this feedback to maintain optimal spacing and prevent transmission degradation, thus resolving the contradiction between high network capacity and transmission quality.
Solution Approach 2:
The patent replaces traditional mechanical wavelength tuning mechanisms with electronic control based on digital measurements. The receiver performs digital coherent reception and FFT processing to measure wavelength spacing electronically, then sends control signals to electronically adjust the transmitter wavelengths, eliminating the need for manual mechanical adjustment and improving both capacity and reliability.
2Measurement precision
If additional measurement devices are added to monitor wavelength spacing, then wavelength control precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the receiver multi-functional by enabling it to perform both its primary function of receiving and demodulating optical signals and the additional function of measuring wavelength spacing. The same digital coherent reception unit and FFT processing unit used for signal demodulation are also used for wavelength measurement, eliminating the need for separate dedicated measurement devices and reducing overall system complexity.
Solution Approach 2:
The patent merges the wavelength measurement function with the existing receiver functionality. The receiver combines the local oscillator signal with the received signal, performs coherent detection, and uses the resulting baseband signal for both data recovery and wavelength spacing measurement through FFT processing, thereby integrating multiple functions into a single device.
3Productivity
If wavelength spacing is reduced to increase channel density, then spectral efficiency is improved, but channel separation becomes more difficult
Solution Approach 1:
The patent replaces physical/optical channel separation methods with electronic signal processing. Instead of using optical filters or physical demultiplexers that become increasingly difficult to implement as channels are packed closer together, the system uses digital coherent reception followed by FFT processing to electronically separate and measure individual channel wavelengths, making channel separation feasible even at very small spacing.
Solution Approach 2:
The patent transforms the channel separation problem from the optical frequency domain into the digital signal processing domain. By performing coherent detection to convert optical signals to electrical baseband signals and then applying FFT in the digital domain, the system separates channels based on their frequency components in the digital spectrum, providing a new dimension for channel separation that is not limited by optical filtering constraints.
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 approach enhances spectral efficiency, reduces transmission degradation, and allows for closer channel spacing without the need for additional measurement devices or costly control signal paths, thereby improving network capacity and performance.
Implementation Method 1
a receiver configured to perform digital coherent reception of the wavelength-multiplexed optical signals
Implementation Method 2
a wavelength spacing monitor configured to transform a reception signal obtained by the digital coherent reception from a time domain signal to a frequency domain spectrum signal
Data Source
AI summary
An optical transmission system includes comprising: a first optical transmission apparatus to transmit wavelength-multiplexed optical signals; and a second optical transmission apparatus to receive the wavelength-multiplexed optical signals, the second optical transmission apparatus including: a receiver to perform digital coherent reception; a wavelength spacing monitor to transform a reception signal obtained by the digital coherent reception from a time domain signal to a frequency domain spectrum signal, and to monitor wavelength spacing of the spectrum signal; and a transmitter to transmit, to the first optical transmission apparatus, wavelength control information according to a monitor result obtained by the wavelength spacing monitor or the monitor result, wherein the first optical transmission apparatus includes: a receiver to receive the wavelength control information or the monitor result; and a control unit to control the wavelength spacing based on the wavelength control information or the monitor result received by the receiver.