Optical Assembly Aligning Waveguide Array to Photonic Integrated Circuit
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Solution Overview
Problem
The challenge lies in effectively optically coupling a waveguide array to a photonic-integrated circuit (PIC) due to the small dimensions of the waveguides on the PIC, which makes precise alignment and coupling of incoming light from external waveguides difficult, and existing methods lack efficiency in maintaining optical alignment and stability.
Innovation Solution
An optical assembly and method using a first and second structure with perpendicular planar surfaces connected via a curable adhesive, allowing for independent adjustment and permanent fixation of the waveguide array's optical paths with the PIC's optical ports, providing five degrees of freedom for alignment and minimizing thermal expansion impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct coupling is used to connect external waveguide to PIC waveguide, then optical coupling is achieved, but alignment precision deteriorates due to large dimension mismatch between external waveguide and PIC waveguide
Solution Approach 1:
The patent introduces an intermediate optical element (lens or microlens array) between the external waveguide and the PIC waveguide. This intermediary component focuses the light from the larger external waveguide onto the smaller PIC waveguide, enabling effective optical coupling despite the dimension mismatch. The intermediary transforms the light distribution to match the target waveguide dimensions.
Solution Approach 2:
The patent employs focusing optics that operate in the optical dimension to bridge the mechanical dimension mismatch. By using lenses to concentrate light in the optical domain, the system achieves coupling between waveguides of different physical dimensions without requiring precise mechanical alignment of the waveguides themselves.
2Reliability
If focusing technique is used to concentrate light onto small spot, then optical coupling to PIC waveguide is improved, but alignment complexity increases due to need for precise positioning
Solution Approach 1:
The focusing lens acts as an intermediary that relaxes alignment requirements. By placing the lens at an appropriate position, it automatically focuses light from a range of input positions onto the target waveguide, reducing the sensitivity to precise positioning and simplifying the alignment process.
Solution Approach 2:
The optical assembly is designed to handle multiple waveguide configurations and dimensions through the use of adjustable focusing optics. The system can adapt to different external waveguide sizes and positions while maintaining effective coupling, providing universal functionality across various coupling scenarios.
3Stability of the object's composition
If adhesive bonding is used to fix waveguide array to substrate, then structural stability is achieved, but thermal expansion effects worsen due to differential expansion between materials
Solution Approach 1:
The patent selects adhesive materials with thermal expansion coefficients that match or compensate for the differential expansion between the substrate and waveguide array materials. By carefully choosing the adhesive's thermal properties, the system minimizes stress and misalignment caused by temperature variations while maintaining structural stability.
Solution Approach 2:
The patent employs composite material structures that combine materials with different thermal expansion properties in a way that balances the overall expansion behavior. The adhesive layer acts as a compliant interface that accommodates differential thermal expansion while maintaining the structural integrity of the assembled components.
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 ensures precise and stable optical alignment and coupling of waveguide arrays to PICs, reducing optical coupling losses and maintaining alignment even after curing, while allowing for efficient optical communication and minimizing thermal expansion effects.
Implementation Method 1
a second structure having a second planar surface connected to the first planar surface of the first structure via an adhesive
Data Source
AI summary
An optical assembly generally having a substrate; a photonic-integrated circuit (PIC) mounted on the substrate, the PIC having a plurality of optical ports; a first structure having a bottom surface connected to the substrate, and a first planar surface extending perpendicularly to the substrate; a second structure having a second planar surface being connected to the first planar surface of the first structure via an adhesive, and a support surface; and a waveguide array having a support surface being connected to the support surface of the second structure, the waveguide array having a plurality of waveguides each defining an optical path, with the optical paths lying in a waveguide plane, the waveguide plane being perpendicular to the first and second planar surfaces, the optical paths being maintained in optical alignment with corresponding ones of the optical ports via the adhered first and second planar surfaces.