Kinematic Optical Connector for Precise Silicon PIC Alignment
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Solution Overview
Problem
Current optical alignment methods for silicon photonic integrated circuits (PICs) with glass waveguide substrates face challenges in achieving robust, efficient, and cost-effective alignment, with passive schemes being susceptible to contamination and active schemes being time-consuming and expensive.
Innovation Solution
A kinematically aligned optical connector is introduced, featuring kinematic connectors and visual fiducials for precise mechanical alignment in six degrees of freedom, allowing for a thicker glass substrate to enhance mechanical strength and minimize warpage, thereby improving alignment accuracy, yield, cost-effectiveness, and assembly throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive alignment schemes are used, then manufacturing cost is reduced, but alignment precision deteriorates due to susceptibility to contamination
Solution Approach 1:
The patent implements preliminary action by pre-defining alignment features (v-grooves, protrusions, recesses) during the glass substrate fabrication process before bonding. These features are created in advance with precise dimensions and positions, eliminating the need for post-bonding alignment adjustments and preventing contamination issues that plague passive alignment methods.
Solution Approach 2:
The patent replaces traditional mechanical alignment systems with a chemically-bonded kinematic mounting system. Instead of relying on mechanical fixtures or active positioning mechanisms susceptible to contamination, the invention uses chemical bonding combined with precisely engineered geometric features (v-grooves at specific angles, complementary protrusions and recesses) to achieve and maintain alignment.
2Manufacturing precision
If active alignment schemes are used, then alignment precision is improved, but productivity deteriorates due to time-consuming processes
Solution Approach 1:
Alignment features are prepared in advance during glass substrate manufacturing, including v-grooves with precise angles (e.g., 54.7 degrees corresponding to silicon <111> facets) and complementary protrusions/recesses. This preliminary preparation eliminates the need for time-consuming active alignment procedures during assembly, as components self-align through their geometric features.
Solution Approach 2:
The kinematic mounting features enable self-alignment and self-positioning during assembly. The protrusion fits into the recess, and the v-groove geometry automatically orients the glass substrate relative to the silicon PIC, eliminating the need for external alignment equipment or time-consuming adjustment procedures.
3Device complexity
If thin glass substrate is used, then device complexity is reduced, but strength deteriorates leading to warpage and misalignment
Solution Approach 1:
The patent applies local quality by creating localized v-groove features and thickness variations in specific regions of the glass substrate. Rather than uniformly thinning the entire substrate (which would compromise strength), the invention locally modifies the glass structure at alignment-critical areas, maintaining overall substrate strength while enabling precise alignment functionality where needed.
Solution Approach 2:
The invention creates a composite structure combining glass substrate, silicon PIC, and adhesive layer in a kinematic mounting arrangement. This composite construction distributes mechanical stresses and prevents warpage, allowing the use of thinner glass substrates without sacrificing strength, as the multi-material assembly provides structural support and stability.
Data Source
AI summary
A kinematically aligned optical connector may be implemented with a silicon PIC component and a glass substrate component. The kinematically aligned optical connector includes one or more kinematic connectors or mechanical alignment features and visual fiducials that enable true kinematic coupling (i.e., in a three-dimensional Cartesian coordinate system, full constraint in all 6 degrees of freedom, meaning, X, Y, Z planes and all 3 angles), and enables an increased thickness of the glass substrate material of the glass waveguide substrate.