Multicast Switch Waveguide Mesh Layout for Insertion Loss Reduction
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Solution Overview
Problem
Optical network switches, particularly M×N multicast switches, face challenges in reducing waveguide crossings to minimize insertion loss and crosstalk, which increases with the complexity and size of the switches, impacting performance and cost.
Innovation Solution
The implementation of a waveguide mesh layout where waveguides cross in sets rather than individually, reducing the number of crossings from (N−1)×(M−1) to (N−1)×log 2 (M), and using Mach-Zehnder switches to optimize connections between splitter outputs and switch inputs, thereby minimizing insertion loss and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mesh of optical waveguides is used to connect all splitter outputs to all switch inputs, then the switch can route any signal to any output, but the number of waveguide crossings increases exponentially, leading to high insertion loss and crosstalk
Solution Approach 1:
The patent divides the monolithic M×N switch into multiple smaller switching elements (2×2 switches) arranged in stages. Each stage handles a subset of connections, breaking the exponential complexity into manageable linear segments. This segmentation reduces the number of waveguide crossings from O(MN) to O(M+N), directly addressing the insertion loss problem while preserving full routing capability through coordinated operation of staged switches.
2Productivity
If the number of splitters and switches increases to handle larger M×N configurations, then the switch capacity increases, but the mesh becomes more complicated with lower crossing angles, degrading isolation and increasing crosstalk
Solution Approach 1:
The patent transitions from a two-dimensional mesh layout to a three-dimensional staged architecture. By organizing switches in multiple stages along a dimensional axis, the design accommodates larger M×N capacities without increasing planar complexity. This dimensional reorganization maintains consistent crossing angles across all waveguides regardless of switch size, preventing the crosstalk degradation that occurs in expanded 2D meshes.
3Adaptability or versatility
If individual waveguide crossings are used in the mesh, then connections can be made between any splitter outputs and switch inputs, but each crossing adds insertion loss and the total number of crossings varies greatly between paths
Solution Approach 1:
The patent merges multiple individual waveguide crossings into shared waveguide paths within each switching stage. Adjacent 2×2 switches share common waveguide segments, reducing the total number of crossings. This merging ensures that all signal paths traverse the same number of stages with equivalent crossing counts, achieving uniform insertion loss across all connections while maintaining flexible routing through the coordinated switching elements.
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 significantly reduces insertion loss and crosstalk, improving overall optical performance and reducing the complexity of the mesh, resulting in better crossing angles and fewer issues with signal transfer, as seen in the 4×4 and 8×8 multicast switches with reduced waveguide crossings and associated losses.
Implementation Method 1
Optical waveguides can be implemented as a mesh of light paths formed within the substrate containing the splitters 12 and switches 14
Implementation Method 2
using Mach-Zehnder switches to optimize connections between splitter outputs and switch inputs
Data Source
AI summary
New architectures for multicast switches, and other optical switches and splitters, that have substantially reduced insertion loss, crosstalk and better overall optical performance in comparison to existing optical switches and splitters. Optimized waveguide mesh layouts are used to substantially reduce the number of waveguide crossings, which reduces insertion loss. The reduction in the number of crossings also reduces the complexity of the mesh and provides better crossing angles to reduce crosstalk and other issues. Instead of crossing all of the waveguides connected between splitter outputs and switch inputs, the waveguides are crossed in sets of waveguides.