Edge Couplers With Grooved Membrane Trenches
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Solution Overview
Problem
Inefficiencies in optical coupling between optical fibers and edge couplers on photonics chips due to mismatched mode size and shape, as well as manufacturing uncertainties and imperfections, result in significant coupling loss.
Innovation Solution
A structure for an edge coupler is developed, featuring a waveguide core with a tapered section and adjacent trenches in a dielectric layer, which enhances mode matching and reduces variability in mode shape and size, promoting efficient butt-end optical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a tapered waveguide core is used for edge coupling, then mode size reduction is achieved, but mode shape mismatch and coupling loss increase
Solution Approach 1:
The patent introduces trenches with specific refractive indices at the edges of the waveguide core, creating local regions with different optical properties. These trenches are positioned specifically where mode matching is needed, allowing the waveguide to maintain its tapered geometry for size reduction while adding local structures that improve mode shape compatibility with optical fibers, thereby reducing coupling loss.
2Ease of manufacture
If fabrication tolerances are relaxed for manufacturing simplicity, then manufacturing precision decreases, but mode shape offsets and coupling inefficiencies increase
Solution Approach 1:
The patent utilizes the refractive index parameter of the trench material as a controllable variable. By selecting materials with specific refractive indices for the trenches, the design can compensate for variations in waveguide core dimensions caused by fabrication tolerances. This parameter adjustment allows the optical mode to be tuned and optimized despite manufacturing variations, maintaining coupling efficiency without requiring extremely tight fabrication tolerances.
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
The proposed structure improves optical coupling efficiency by aligning the mode shape and size of the laser light with the waveguide core, reducing coupling loss and variability caused by fabrication tolerances and refractive index uncertainties.
Implementation Method 1
The waveguide core region has a tapered section with an end surface that terminates adjacent to the edge of the first dielectric layer
Implementation Method 2
The second dielectric layer includes a first trench and a second trench that are each positioned adjacent to the tapered section of the waveguide core region
Data Source
AI summary
Structures including an edge coupler and methods of fabricating a structure including an edge coupler. The structure includes a waveguide core region on a first dielectric layer, and a second dielectric layer on the waveguide core region and the first dielectric layer. The waveguide core region has a tapered section with an end surface that terminates adjacent to an edge of the first dielectric layer. The second dielectric layer includes a first trench and a second trench that are each positioned adjacent to the tapered section of the waveguide core region.