Flexible Interposer for Passive Optical Coupling to Photonic Integrated Circuits
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Solution Overview
Problem
Coupling multiple optical fibers to a photonic integrated circuit (PIC) chip is challenging due to the need for sub-micron precision alignment, which is costly and difficult with existing methods, especially for passive alignment solutions.
Innovation Solution
An interposer with flexible optical waveguide members is used to connect standard optical fibers to a PIC chip, allowing for passive alignment with sub-micron tolerance, enabling high-density optical connections and simultaneous optical and electrical testing without the need for cleaving the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard methods are used to attach one or two fibers to a single PIC output/input waveguide, then optical coupling precision is improved, but cost increases
Solution Approach 1:
The system divides the optical coupling task into multiple independent waveguide arrays, each handling a portion of the total fiber connections. This segmentation allows standard precision methods to be applied to each array individually while reducing the overall complexity and cost compared to attaching all fibers directly to a single waveguide.
Solution Approach 2:
The invention creates a universal interface platform that can accommodate multiple fiber connections simultaneously. The waveguide arrays provide a multi-functional solution that replaces multiple individual attachment operations, achieving both high precision optical coupling and cost-effective manufacturing through standardized array structures.
2Measurement precision
If lensed fiber arrays with accurate alignment are used for multiple fiber connections, then optical coupling precision is improved, but device complexity and cost increase
Solution Approach 1:
The invention introduces waveguide arrays as an intermediary structure between the fiber array and the PIC chip. This intermediary provides a standardized interface that simplifies the alignment process, allowing passive alignment techniques to achieve sub-micron precision without the complexity of active alignment procedures required by direct fiber-to-chip coupling methods.
Solution Approach 2:
The system changes the alignment parameter regime by using waveguide arrays with dimensions and spacing that enable passive alignment. The waveguide array structure transforms the alignment tolerance requirements into a regime where standard fabrication precision (micron-level) is sufficient, eliminating the need for complex active alignment procedures.
3Reliability
If active alignment methods are used to optimize optical coupling, then optical coupling efficiency is improved, but manufacturing time and complexity increase
Solution Approach 1:
The waveguide arrays are pre-fabricated with precise geometric dimensions and spacing that encode the alignment information. This preliminary action during fabrication eliminates the need for post-assembly active alignment, as the structures are designed to self-align passively when brought together, maintaining high optical coupling efficiency while simplifying the manufacturing process.
4Measurement precision
If multiple fibers are coupled to a PIC chip with sub-micron precision, then optical coupling precision is improved, but the difficulty of alignment increases
Solution Approach 1:
The system segments the multiple fiber connections into separate waveguide array modules. Each array handles a subset of connections with relaxed alignment requirements, and the modular structure allows independent alignment of each array, significantly reducing the overall alignment difficulty compared to aligning all fibers simultaneously to a single chip surface.
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 approach facilitates accurate, high-density, and cost-effective optical coupling with reduced thermal expansion mismatch, enabling on-wafer optical characterization and testing, and provides flexibility in fiber usage, allowing for temporary or permanent connections.
Implementation Method 1
one or more flexible optical waveguide members (112, 114, 116). The flexible optical waveguide members each include an optical waveguide
Data Source
Figure 1A~1B
Figure 1C~2A
Figure 2B~3A
AI summary
Improved passive optical coupling to photonic integrated circuit (PIC) chips is provided. An interposer unit having one or more flexible optical waveguide members is employed. The flexible optical waveguide members are coupled to the PIC chip via their tips. The PIC chip includes alignment features to facilitate lateral, vertical and longitudinal passive alignment of the flexible optical waveguide members to on-chip optical waveguides of the PIC.