Facet-Spacer Alignment for Passive Optical Waveguide Edge Coupling
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Solution Overview
Problem
Current optical data communication systems face challenges in achieving precise and cost-effective alignment and coupling of optical waveguides between chips, requiring active optical alignment processes that are time-consuming and expensive, and using index-matched epoxy which degrades under high optical intensities.
Innovation Solution
Implementing photolithographically defined spacers on chip facets to passively control the alignment of optical waveguides, maintaining a controlled air gap without active alignment techniques and index-matched epoxy, using micrometer- or sub-micrometer-level precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If active optical alignment processes are used to achieve precise alignment of optical waveguides, then alignment precision is improved, but manufacturing time and cost increase
Solution Approach 1:
Alignment features (such as protrusions and recesses, or spacers) are pre-formed on the chip surfaces during fabrication. These features passively guide and constrain the relative positioning of chips during assembly, eliminating the need for time-consuming active optical alignment processes while maintaining precise alignment of optical waveguides
Solution Approach 2:
The alignment features on the chip surfaces automatically perform the alignment function during assembly through mechanical interlocking or spacer-based positioning. The system self-aligns without requiring external active optical measurement or adjustment equipment, thereby reducing manufacturing time and cost while achieving precise waveguide alignment
2Reliability
If index-matched epoxy is used to couple optical waveguides, then coupling efficiency is improved, but reliability deteriorates under high optical intensities
Solution Approach 1:
The patent removes the epoxy coupling medium from the system entirely. Instead, optical waveguides are directly coupled through physical contact or a controlled air gap between chips. This eliminates the epoxy's vulnerability to optical intensity degradation while maintaining efficient optical coupling through direct waveguide-to-waveguide coupling
Solution Approach 2:
Alignment features (protrusions, recesses, or spacers) serve as mechanical intermediaries that enable precise positioning and stable coupling of optical waveguides without requiring epoxy. These features provide the necessary mechanical support and alignment while allowing direct optical coupling between waveguides, eliminating the need for epoxy-based coupling
Data Source
AI summary
A first chip includes a first plurality of optical waveguides exposed at a facet of the first chip. A second chip includes a second plurality of optical waveguides exposed at a facet of the second chip. The second chip includes first and second spacers on opposite sides of the second plurality of optical waveguides. The first and second spacers have respective alignment surfaces oriented substantially parallel to the facet of the second chip at a controlled perpendicular distance away from the facet of the second chip. The second chip is positioned with the alignment surfaces of the first and second spacers contacting the facet of the first chip, and with the second plurality of optical waveguides respectively aligned with the first plurality of optical waveguides. The first and second spacers define and maintain an air gap of at least micrometer-level precision between the first and second pluralities of optical waveguides.