Pluggable Fiber-to-Chip Coupling With Passive Alignment Features
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Solution Overview
Problem
Conventional fiber-to-chip coupling methods face challenges such as irreversible attachment leading to system failures, limited pitch and alignment accuracy, interference with silicon components, and high insertion loss, especially with v-groove-based techniques.
Innovation Solution
A pluggable fiber-attach-first technique using passive alignment features like alignment pillars and cavities, eliminating v-grooves, enabling sub-half-micron precision and small mode-field-diameter couplers, and allowing for evanescent coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If v-groove-based coupling techniques are used, then alignment can be achieved, but insertion loss increases and manufacturing precision deteriorates
Solution Approach 1:
The patent removes the v-groove structure from the silicon substrate, extracting the harmful element that caused both high insertion loss and limited alignment precision. By eliminating the v-groove-based coupling mechanism, the invention enables direct waveguide-to-waveguide coupling with sub-half-micron precision while reducing optical energy loss.
Solution Approach 2:
The patent replaces the mechanical v-groove alignment system with an optical coupling system using evanescent coupling between waveguides. This substitution eliminates the need for mechanical groove structures and achieves superior alignment precision through optical field interaction, thereby reducing insertion loss.
2Manufacturing precision
If v-groove-based techniques are used, then coupling can be achieved, but alignment precision is limited
Solution Approach 1:
By removing the complex v-groove structure from the silicon substrate, the patent simplifies the overall device architecture while achieving sub-half-micron alignment precision through alternative waveguide coupling mechanisms that require minimal structural complexity.
Solution Approach 2:
The patent changes the coupling mechanism from mechanical v-groove-based alignment to optical evanescent coupling, fundamentally altering how alignment is achieved. This parameter change enables higher precision without increasing structural complexity, as the optical field naturally guides alignment.
3Reliability
If irreversible attachment methods are used, then coupling can be achieved, but system reliability decreases
Solution Approach 1:
The patent implements a dynamic, reversible attachment process using mechanical features that allow the glass substrate to be securely attached during manufacturing and then easily removed or repositioned. This dynamic approach maintains system reliability by preventing permanent damage while simplifying the manufacturing process through controlled mechanical engagement.
4Manufacturing precision
If conventional coupling methods are used, then alignment can be achieved, but pitch is limited
Solution Approach 1:
By removing the v-groove structure that imposed fixed pitch constraints, the patent enables flexible pitch design. The waveguide coupling mechanism can accommodate various pitch values without being constrained by groove geometry, thereby improving adaptability while maintaining sub-half-micron alignment precision.
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
Enables efficient, high-yield coupling with improved alignment accuracy and reduced insertion loss, facilitating integration with silicon components and reducing the risk of breakage.
Implementation Method 1
The alignment features of the photonic stack and the glass substrate are configured to passively align the glass substrate with the photonic stack
Implementation Method 2
The one or more waveguides in the photonic stack and the one or more glass waveguides of the glass substrate are optically coupled via edge coupling or evanescent coupling
Implementation Method 3
applying mechanically strong epoxy between the glass substrate and the photonic stack to secure the glass substrate with the photonic stack
Data Source
AI summary
Described herein are pluggable fiber-attach-first techniques and related manufacturing methods for assembling photonic chips according to the fiber-attach-first technique. The techniques may be used in several fields including, but not limited to, 2D, 2.5D, and 3D package architectures, wafer scale packaging technologies, and transceiver technologies. A photonic device comprises a photonic stack, a glass substrate and epoxy configured to hold the photonic stack and the glass substrate together. The photonic stack comprises one or more alignment features. The glass substrate comprises one or more alignment features, wherein each of the one or more alignment features of the glass substrate engage with a corresponding alignment feature of the photonic stack such that one or more waveguides of the photonic stack are optically coupled with one or more glass waveguides of the glass substrate.