Evanescent Coupling Between Non-Coplanar Waveguides
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Solution Overview
Problem
Existing optical interconnects between non-coplanar waveguides, such as those on different substrates or chips, require precise alignment to achieve efficient evanescent coupling, which is prone to misalignment issues during manufacturing and use, leading to high losses and inefficiencies.
Innovation Solution
The optical system comprises two waveguides positioned in different planes, configured with spiral or ring shapes to form multiple coupling regions, allowing for evanescent coupling with tolerance to relative translation and rotation, reducing sensitivity to misalignment and eliminating the need for auxiliary coupling elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional coupling methods (optical fiber, tapered waveguides, gratings) are used to connect optical chips, then coupling can be achieved, but alignment accuracy requirements are high and losses are large
Solution Approach 1:
The patent introduces an evanescent field coupling mechanism as an intermediary between two waveguides on different substrates. The evanescent field extends from the first waveguide into the second substrate, enabling energy transfer without direct physical contact or precise alignment. This intermediary field allows coupling while tolerating misalignment and reducing losses compared to traditional methods.
Solution Approach 2:
The patent replaces mechanical alignment systems (optical fibers, tapered waveguides, gratings) with a field-based coupling mechanism. Instead of relying on mechanical precision and physical intermediaries, the system uses evanescent electromagnetic fields to transfer energy, eliminating the need for high-precision mechanical alignment structures.
2Manufacturing precision
If evanescent wave coupling is used between waveguides on different substrates, then alignment tolerance can be improved, but coupling efficiency is reduced due to distance
Solution Approach 1:
The patent moves the coupling interaction from a lateral (in-plane) dimension to a vertical (through-substrate) dimension. By positioning waveguides on different substrates stacked vertically, the evanescent field can couple through the substrate thickness, providing alignment tolerance in the lateral dimensions while maintaining efficient coupling through optimized vertical spacing.
Solution Approach 2:
The patent optimizes parameters such as substrate thickness, waveguide spacing, and evanescent field penetration depth to balance alignment tolerance and coupling efficiency. By adjusting these parameters, the system achieves sufficient tolerance to lateral misalignment while maintaining high coupling efficiency through controlled field interaction strength.
3Loss of energy
If waveguides are positioned fixed with respect to each other (as in co-planar configurations), then coupling efficiency can be maximized, but tolerance to rotation and translation during manufacturing and installation is lost
Solution Approach 1:
The patent transitions from co-planar (2D) waveguide positioning to stacked (3D) configuration on different substrates. This vertical stacking provides rotational and translational tolerance in the lateral plane while maintaining controlled coupling through the vertical dimension, enabling both efficiency and adaptability.
Solution Approach 2:
The patent creates an asymmetric coupling geometry where the first waveguide is on one substrate and the second waveguide is on a different substrate at a different position. This asymmetric arrangement provides inherent tolerance to rotation and translation while maintaining efficient evanescent field coupling through optimized spatial separation.
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 configuration achieves high coupling efficiency with reduced sensitivity to horizontal and angular misalignments, enabling efficient radiation transfer between non-coplanar waveguides with improved manufacturing tolerance and reduced production complexity.
Implementation Method 1
the first waveguide being stacked over the second waveguide at a distance adapted to allow evanescent coupling between the first waveguide and the second waveguide
Data Source
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AI summary
An optical system for obtaining radiation coupling between two waveguides positioned non-coplanar is described. The system comprises a first waveguide positioned in a first plane and a second waveguide positioned in a second plane, the first waveguide being stacked over the second waveguide at a distance adapted to allow evanescent coupling between the first waveguide and the second waveguide. The first and second waveguides are configured such that the coupling is at least partly tolerant to relative translation or rotation of the waveguides with respect to each other.