Optical Reception Device Wavelength Control for Coherent Transmission
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Solution Overview
Problem
In optical access networks, the cost of ONUs increases the unit device cost per user, and installing a wavelength locker in ONUs for digital coherent transmission is costly, making it difficult to apply this technology at a low cost while increasing the transmission distance.
Innovation Solution
An optical reception device that generates multiple local lights with different wavelengths, selects a local light close to the received optical signal, and uses a wavelength detection unit to control the local light transmission, allowing for coherent reception without a wavelength locker, thereby increasing the range of frequency variation and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a wavelength locker is installed in ONUs for digital coherent transmission, then transmission distance can be increased, but device cost increases
Solution Approach 1:
The invention extracts the wavelength locker function from the ONU and relocates it to the OLT side. The ONU transmits optical signals without a wavelength locker, while the OLT performs wavelength detection and local light transmission to compensate for frequency offsets. This extraction eliminates the need for expensive wavelength lockers in each ONU, reducing device cost while maintaining transmission distance through coherent reception at the OLT.
Solution Approach 2:
The invention introduces an intermediary wavelength detection unit at the OLT that mediates between the transmitted optical signal and the local light generation. This intermediary detects the wavelength of incoming signals and controls the transmission of appropriate local lights, enabling frequency offset compensation without requiring wavelength lockers in the ONUs. The intermediary acts as a centralized control mechanism that replaces distributed wavelength locking functionality.
2Measurement precision
If multiple local lights with different wavelengths are generated and selected, then coherent reception accuracy improves, but device complexity increases
Solution Approach 1:
The invention segments the wavelength range into multiple discrete channels, each handled by a dedicated local light source. Instead of using a single broadband local light, the system divides the spectrum and assigns specific wavelength ranges to specific local lights. This segmentation enables precise wavelength matching for coherent reception while simplifying control through discrete, manageable wavelength bands rather than continuous tuning.
Solution Approach 2:
The invention implements dynamic wavelength selection where the system adapts to the actual wavelength of incoming optical signals by selecting appropriate local lights based on detected wavelength. The wavelength detection unit continuously monitors incoming signals and dynamically controls which local lights are transmitted, allowing the system to adapt to wavelength variations without manual configuration or fixed wavelength assumptions.
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 enables increased transmission distance while reducing costs by allowing coherent reception without the need for a wavelength locker, enhancing the cost-effectiveness of digital coherent transmission in optical access networks.
Implementation Method 1
a local light transmission unit that generates a plurality of local lights having different wavelengths
Implementation Method 2
split the input optical signal into different paths according to wavelengths by using a wavelength multiplexer/demultiplexer
Implementation Method 3
coherent reception being performed, and a signal can be received with a signal-to-noise ratio that is close to a shot noise limit
Data Source
AI summary
An optical reception device including: a local light transmission unit configured to generate a plurality of local lights having different wavelengths, select a local light having a wavelength that is close to the wavelength of a received optical signal from among the plurality of generated local lights having different wavelengths, and transmit the selected local light to a coherent receiver; a demultiplexing unit configured to demultiplex a received optical signal and transmit the demultiplexed optical signal to the coherent receiver via a first path; and a wavelength detection unit configured to input the optical signal demultiplexed by the demultiplexing unit via a second path, split the input optical signal into different paths according to wavelengths by using a wavelength multiplexer/demultiplexer, and output, to the local light transmission unit, a control signal for causing the local light transmission unit to output a local light having a frequency that corresponds to a path in which the optical signal is included.