Metamaterial Edge Couplers for Photonics Chip Power Loss
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Solution Overview
Problem
Conventional photonics chips experience significant power loss due to the large mode size mismatch between optical fibers and edge couplers, leading to inefficient coupling of laser light.
Innovation Solution
A structure for an edge coupler is developed, featuring a waveguide core with a tapered section and a back-end-of-line stack that includes interlayer dielectric layers and features positioned adjacent to the side edge, allowing for efficient coupling by overlapping with the tapered section of the waveguide core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct butt-coupling is used between optical fiber and edge coupler, then coupling structure is simple, but power loss is significant due to mode size mismatch
Solution Approach 1:
The patent introduces a groove structure that extends into the substrate, creating a vertical dimension for light confinement. This dimensional change allows the optical mode to be confined more effectively at the edge coupler interface, enabling better mode matching between the optical fiber and waveguide without adding lateral complexity to the coupling structure.
Solution Approach 2:
The groove acts as an intermediary structure between the optical fiber and the edge coupler. By introducing this intermediate feature, the patent enables gradual mode transformation and improves coupling efficiency without requiring complex alignment mechanisms or additional optical components.
2Ease of manufacture
If conventional edge coupler structure is used, then manufacturing process is simple, but coupling efficiency is low due to mode size mismatch
Solution Approach 1:
The patent segments the edge coupler structure by introducing a groove that divides the substrate into distinct regions. This segmentation creates separate functional zones for light input, mode transformation, and waveguide coupling, allowing each segment to be optimized independently while maintaining overall manufacturing simplicity.
Solution Approach 2:
The patent modifies the physical parameters of the edge coupler by introducing a groove with specific dimensions (depth, width, and shape). These parameter changes alter the optical field distribution and mode confinement, significantly improving coupling efficiency without fundamentally changing the manufacturing process flow.
3Reliability
If optical components are formed during middle-of-line and front-end-of-line processing, then optical component performance is optimized, but back-end-of-line stack cannot be integrated with optical components
Solution Approach 1:
The patent merges the optical component formation process with the back-end-of-line stack formation by introducing the groove structure during middle-of-line processing. This merging allows the optical components and the back-end stack to be integrated seamlessly, as the groove structure is compatible with both optical fabrication techniques and subsequent metal layer deposition processes.
Solution Approach 2:
The groove structure serves multiple functions: it confines optical modes, defines the edge coupler geometry, and provides a foundation for subsequent metal layer integration. This multi-functionality allows the same structural feature to support both high-performance optical operation and seamless integration with the back-end-of-line stack.
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 reduces power loss by aligning the optical fiber directly with the side edge of the back-end-of-line stack, promoting efficient coupling of optical signals without the need for a groove, thereby enhancing the operational efficiency of photonics chips.
Implementation Method 1
Metamaterial edge couplers in the back-end-of-line stack of a photonics chip
Data Source
AI summary
Structures for an edge coupler and methods of forming a structure for an edge coupler. The structure includes a waveguide core over a dielectric layer, and a back-end-of-line stack over the waveguide core and the dielectric layer. The back-end-of-line stack includes an interlayer dielectric layer, a side edge, a first feature, a second feature, and a third feature laterally arranged between the first feature and the second feature. The first feature, the second feature, and the third feature are positioned on the interlayer dielectric layer adjacent to the side edge, and the third feature has an overlapping relationship with a tapered section of the waveguide core.