Fiber Array Coupler With Optical Window for Passive Chip Alignment
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Solution Overview
Problem
Photonic chips with Through Silicon Vias (TSVs) face challenges in edge coupling due to their thinness, which restricts the creation of deep trenches for lens or fiber placement, and conventional edge coupling techniques cannot be used, necessitating innovative alignment and attachment methods for optical components.
Innovation Solution
A fiber array unit with alignment protrusions and optical windows is designed for passive alignment with photonic chips, using a die bonder for precise alignment and epoxy bonding, allowing for efficient optical fiber alignment and curing without active alignment feedback, suitable for TSV-compatible photonic chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional edge coupling techniques are used with TSV photonic chips, then optical signal transmission is achieved, but the thinness of TSV chips prevents deep trench formation for lens or fiber placement
Solution Approach 1:
The patent transitions from conventional edge coupling (requiring deep trenches in the chip plane) to vertical coupling through the chip surface. By changing the coupling dimension from lateral to vertical, the invention accommodates the thinness of TSV chips while maintaining optical signal transmission capability.
Solution Approach 2:
Instead of placing lenses or fibers in deep trenches at the chip edge (conventional approach), the invention inverts the approach by creating protrusions that extend upward from the chip surface, allowing optical components to couple vertically from above rather than from the edge.
2Manufacturing precision
If active alignment feedback is used for fiber alignment, then alignment precision is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The alignment protrusions are designed with self-aligning geometric features that automatically guide the fiber array unit into precise alignment with the photonic chip during the bonding process. This self-service alignment mechanism eliminates the need for external active alignment feedback systems, reducing both complexity and cost while maintaining precision.
Solution Approach 2:
The alignment protrusions are pre-formed on the photonic chip before fiber attachment. These pre-formed features serve as mechanical guides that passively align the fiber array unit during bonding, eliminating the need for post-bonding active alignment adjustments.
3Ease of manufacture
If wire bond based interconnection is used, then peripheral bond pad space is utilized, but interconnect density and resistance are limited
Solution Approach 1:
The patent replaces the mechanical wire bond interconnection system with a direct TSV-based electrical interconnection system. This substitution eliminates the need for peripheral bond pads and wire bonds, enabling higher interconnect density and reduced resistance by utilizing the vertical TSV pathways through the chip substrate.
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 solution enables precise and cost-effective alignment and attachment of optical fibers to photonic chips with TSVs, enhancing optical coupling efficiency and reducing manufacturing costs by eliminating the need for active alignment and complex trench formation.
Implementation Method 1
The optical window is configured to permit radiation to pass through the layer of non-transparent material to cure epoxy with which the plurality of optical fibers is bonded to the photonic chip
Data Source
AI summary
A fiber array unit (FAU) includes a substrate, a plurality of optical fibers, and a lid. The substrate includes: an optical window extending through a layer of non-transparent material, a plurality of grooves, and an alignment protrusion configured to mate with an alignment receiver. The plurality of optical fibers are disposed in the plurality of grooves. The alignment protrusion is configured to align the plurality of optical fibers with an external device when mated with the alignment receiver. The plurality of optical fibers is disposed between the lid and the substrate.