Multi-Fiber Interface to Photonic Subassembly Alignment
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Solution Overview
Problem
The high cost and complexity of aligning optical fibers with photonic subassemblies, particularly due to tight manufacturing tolerances and the use of expensive materials, hinder the widespread adoption of fiber optic technology in local metropolitan area communication networks.
Innovation Solution
A multiple piecepart alignment configuration comprising a box-shaped fiber holder, a grooved lid, and a silicon photonic subassembly, where the fiber holder sets initial fiber spacing and elevation, and the grooved lid and silicon subassembly provide progressively tighter alignment through registration features and etched channels, allowing for alignment tolerances of ±2 μm in the x-axis and ±10 μm in the y and z axes, using relatively inexpensive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional single-piece alignment methods are used, then alignment precision can be achieved, but manufacturing cost increases and manufacturing complexity increases
Solution Approach 1:
The alignment system is divided into multiple independent components: a fiber array assembly with V-groove substrate, a separate alignment substrate with etched channels, and a housing structure. This segmentation allows each component to be manufactured separately with relaxed tolerances using inexpensive materials, while achieving tight overall alignment through the hierarchical alignment mechanism.
Solution Approach 2:
The fiber array is pre-aligned within the V-groove substrate before final assembly, and the alignment substrate is pre-patterned with etched channels that define the final alignment positions. These preliminary alignment actions enable the final assembly to achieve precise alignment without requiring tight tolerances on all components.
2Manufacturing precision
If tight alignment tolerances are imposed on all components, then alignment accuracy improves, but device complexity increases and ease of manufacture deteriorates
Solution Approach 1:
The alignment function is segmented across multiple components with different precision requirements. The V-groove substrate provides initial fiber positioning, the alignment substrate with etched channels provides intermediate positioning, and the housing provides final mechanical alignment. This segmentation allows most components to have relaxed tolerances while achieving tight overall alignment.
Solution Approach 2:
The alignment substrate acts as an intermediary element between the fiber array and the housing. It features etched channels that guide and position the fiber array, providing a mechanical mediation that translates relaxed tolerances from individual components into tight overall alignment without increasing device complexity.
3Manufacturing precision
If expensive materials are used for alignment components, then manufacturing precision improves, but manufacturing cost increases
Solution Approach 1:
The system uses multiple inexpensive substrate materials (such as ceramics, plastics, or metals) instead of expensive precision materials throughout. Each substrate is manufactured separately using conventional, low-cost processes, and the hierarchical alignment mechanism achieves precise positioning without requiring expensive materials.
Solution Approach 2:
The invention employs inexpensive substrates and alignment components that can be manufactured using conventional, low-cost processes. The design accepts that these components may have shorter lifetimes or lower individual precision, but the hierarchical alignment system compensates to achieve the required overall precision at low cost.
Data Source
AI summary
A multiple piecepart alignment and attachment configuration for mating a fiber array (or even a single fiber) with a silicon photonic subassembly utilizes ever-tightening alignment tolerances to align the fiber array with a similar array of waveguides (or other devices) formed within the photonic subassembly. A box-shaped fiber holder is formed to include a plurality of grooves within its bottom interior surface to initially support the fiber array. A separate piecepart in the form of a lid is mated to, and aligned with, the silicon photonic subassembly. The lid is formed to include registration features on its underside that fit into alignment detents formed in the top surface of the silicon photonic subassembly upon attachment. The lid also includes a number of grooves formed on its underside that will capture the top surface of the fibers as the fiber holder is slide into place over the lid. The grooves within the lid function to tighten the pitch of the fiber array and ultimately control the lateral and vertical alignment between the fiber array and the subassembly. The subassembly is also formed to include etched channels along the endface (the channels aligned with optical waveguides/devices in the substrate) to mate with the fiber holder, where the optical fibers are ultimately positioned within the channels so as to be in alignment with the optical waveguides/devices.