Shared Laser Synchronization for Metro Network Coherent Detection
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Solution Overview
Problem
In metro networks, the high cost and complexity of the primary node are increased due to the need for multiple local oscillator lasers and optical hybrid circuits to coherently detect upstream optical signals from multiple secondary nodes, which complicates the design and increases expenses.
Innovation Solution
Each secondary node shares a laser for both transmission and reception, with its frequency synchronized with the primary node's laser, allowing a single primary node laser and optical hybrid circuit to detect all upstream signals, reducing the number of components needed in the primary node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple local oscillator lasers and optical hybrid circuits are provided in the primary node to coherently detect upstream optical signals from multiple secondary nodes, then coherent detection capability and receiver sensitivity are improved, but device complexity and cost increase
Solution Approach 1:
A single local oscillator laser and optical hybrid circuit in the primary node are designed to serve multiple secondary nodes through frequency tuning capability. The laser can be tuned to different frequencies to match the upstream signals from different secondary nodes, allowing one component to perform the function of multiple dedicated lasers and hybrid circuits would otherwise be needed.
Solution Approach 2:
The patent employs dynamic frequency tuning of the local oscillator laser to adapt to different upstream signal frequencies from various secondary nodes. This dynamic adjustment allows the same hardware components to maintain coherent detection capability across multiple nodes without requiring static dedicated components for each node.
2Reliability
If multiple local oscillator lasers and optical hybrid circuits are provided in the primary node to coherently detect upstream optical signals from multiple secondary nodes, then coherent detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent designs a universal detection system where a single local oscillator laser and optical hybrid circuit can detect upstream signals from multiple secondary nodes. This multi-functional approach replaces the need for multiple dedicated detection circuits, significantly reducing component count, manufacturing complexity, and overall system cost while maintaining coherent detection capability.
3Reliability
If each secondary node uses its own local oscillator laser for coherent detection, then receiver sensitivity is maintained, but the number of components and system complexity increase
Solution Approach 1:
The patent merges the local oscillator laser functions from multiple secondary nodes into a single shared laser resource at the primary node. By combining multiple dedicated lasers into one tunable laser that serves all nodes, the system reduces the total number of laser components while maintaining the ability to provide coherent detection with high receiver sensitivity for each node.
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 simplifies the primary node design, reduces costs, and maintains high receiver sensitivity and capacity by enabling coherent detection across all secondary nodes with minimal additional complexity.
Implementation Method 1
coherent detection is employed in each secondary node to achieve high receiver sensitivity and to extract amplitude, frequency, and phase information from the received optical signals
Implementation Method 2
The local oscillator laser, in conjunction with the optical hybrid circuit serve to 'beat' with the incoming optical signals from the primary node to down convert the received optical signals to the baseband
Implementation Method 3
an optical splitter, which may supply a power-split portion of each optical signal to a corresponding secondary nodes
Implementation Method 4
optical signals are transmitted from each secondary node are combined by an optical combiner and output to the primary node
Data Source
AI summary
Consistent with the present disclosure a network is provided that includes a primary node and a plurality of secondary nodes. The primary node, as well as each of the secondary nodes, includes a laser that is “shared” between the transmit and receive sections. That is, light output from the laser is used for transmission as well as for coherent detection. In the coherent receiver, the frequency of the primary node laser is detected and, based on such detected frequency, the frequency of the secondary node laser is adjusted to detect the received information or data. Such frequency detection also serves to adjust the transmitted signal frequency, because the laser is shared between the transmit and receive portions in each secondary receiver. Light output from the primary node laser, which is also shared between transmit and receive portions in the primary node, is thus also set to a frequency that permits detection of each of the incoming optical signals by way of coherent detection. Since, in this example, only one laser is employed in the primary node, the primary node may have a simpler design and may be less expensive to manufacture compared to a primary node having multiple local oscillator lasers, each associated with a corresponding uplink optical signal.