Back-End-of-Line Grating Optical Couplers for Photonics Integration
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Solution Overview
Problem
Conventional photonics chips lack integrated grating and waveguide structures in the multilayer stack, limiting the efficient transfer of light between optical components and increasing the layout area and operational overhead.
Innovation Solution
A multilayer structure with optical couplers that include a first grating and a second grating, where the second grating is positioned in a different level with metal segments overlapping the first grating, and a waveguide core connected to a plasmonic component, allowing for efficient light transfer through phase matching and material heterogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional optical couplers are used without gratings in the multilayer stack, then the fabrication process is simpler, but light transfer efficiency between optical components is limited
Solution Approach 1:
The patent embeds gratings within the multilayer stack structure, nesting optical coupling elements inside the existing fabrication layers. The first and second gratings are positioned at different levels within the stack, allowing efficient light transfer while maintaining compatibility with standard fabrication processes.
Solution Approach 2:
The patent transitions from planar optical coupling to three-dimensional coupling by positioning gratings at different vertical levels within the multilayer stack. The first grating is at a first level and the second grating is at a second level, enabling vertical light transfer paths that improve coupling efficiency.
2Area of stationary object
If optical components are densely integrated on the chip, then the layout area is reduced, but the operational overhead and fabrication complexity increase
Solution Approach 1:
The patent utilizes the vertical dimension of the multilayer stack to accommodate optical components and gratings at different levels. This three-dimensional arrangement allows dense integration of optical components while maintaining clear separation of functions, thereby reducing layout area without proportionally increasing operational overhead.
Solution Approach 2:
The multilayer stack structure serves multiple functions simultaneously: it provides mechanical support, electrical isolation through interlayer dielectric layers, and optical coupling pathways through embedded gratings. This multi-functionality reduces the need for separate dedicated structures, lowering operational overhead despite high integration density.
3Adaptability or versatility
If gratings are formed during middle-of-line or front-end-of-line processing, then the optical components can be integrated, but the light coupling efficiency between components is insufficient
Solution Approach 1:
The patent nests gratings within the multilayer stack formed during back-end-of-line processing. The first grating and second grating are embedded at different levels within the stack, creating efficient coupling pathways that were not achievable with conventional single-level grating structures.
Solution Approach 2:
The patent optimizes light coupling by positioning gratings at different vertical levels and adjusting their spatial arrangement. The first grating at a first level and the second grating at a second level create specific optical path lengths and phase relationships that enhance coupling efficiency between optical components.
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 solution enables efficient light coupling and energy transfer, reducing the form factor of the optical coupler and increasing the density of optical components on the photonics chip, while promoting phase matching and material efficiency.
Implementation Method 1
allowing for efficient light transfer through phase matching and material heterogeneity
Implementation Method 2
a plasmonic component, and a waveguide core connected to the optical component. The waveguide core is positioned in a first level over the first dielectric layer
Implementation Method 3
a waveguide core connected to the optical component
Data Source
AI summary
Structures including an optical coupler and methods of fabricating a structure including an optical coupler. The structure includes a substrate, a first dielectric layer on the substrate, and an optical coupler having a first grating and a second grating. The first grating has a first plurality of segments positioned in a first level over the first dielectric layer. The second grating has a second plurality of segments positioned in a second level over the first dielectric layer. The second level differs in elevation above the first dielectric layer from the first level. The second plurality of segments are positioned in the second level to overlap with the first plurality of segments of the first grating, and the second plurality of segments comprise a metal. A second dielectric layer is positioned in a vertical direction between the first level and the second level.