Marker Waveguide Alignment for Edge-Coupled Photonic ICs
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Solution Overview
Problem
The challenges in packaging and aligning edge coupled photonic integrated circuits (PICs) with external optical components, particularly due to the difficulty in viewing and aligning waveguides, especially in flipchip mounting configurations, hinder the adoption of edge couplers despite their superior performance.
Innovation Solution
Incorporating marker waveguides with grating couplers that illuminate edge couplers to facilitate precise alignment by coupling light into the waveguides, enabling active alignment using external light sources, and employing alignment waveguides for both lateral and angular alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If edge couplers are used to interface with external optical components, then coupling bandwidth and polarisation performance are improved, but packaging and alignment difficulty increases
Solution Approach 1:
The patent incorporates alignment waveguides and coupling structures during the photonic integrated circuit fabrication process itself, rather than during final packaging. These pre-formed alignment features enable automatic or semi-automatic alignment of edge couplers to external optical components, eliminating the need for complex manual packaging alignment procedures while maintaining wide bandwidth performance
Solution Approach 2:
The patent introduces alignment waveguides as intermediary structures that facilitate the alignment process. These specialized waveguides include features such as alignment marks, coupling gaps, and positioning structures that mediate between the photonic circuit and external optical components, enabling precise alignment without requiring direct visualization of the actual functional waveguides
2Measurement precision
If waveguides are made visible for alignment purposes, then alignment precision is improved, but device structure becomes more complex
Solution Approach 1:
The patent segments the waveguide system into two distinct types: functional waveguides that carry optical signals and alignment waveguides that are specifically designed to be visible and alignable. The alignment waveguides are separate structures with simplified geometries and visible features, while functional waveguides maintain their optimized signal transmission characteristics. This segmentation allows alignment without compromising functional performance
Solution Approach 2:
The patent creates alignment waveguides that are simplified copies or representations of the functional waveguides. These alignment waveguides replicate the essential geometric features and positioning characteristics of the functional waveguides but with enhanced visibility and alignment features. The alignment waveguides serve as optical copies that can be manipulated and aligned independently, then used to position the actual functional waveguide structures
3Ease of operation
If active alignment with external light sources is used, then alignment capability is improved, but device cost increases
Solution Approach 1:
The patent incorporates self-aligning features directly into the photonic integrated circuit structure during fabrication. Alignment waveguides include intrinsic alignment features such as asymmetric geometries, colored or contrasting material regions, and pre-positioned coupling structures that enable the device to self-align with external optical components without requiring external light sources or complex alignment equipment. The alignment information is embedded within the device structure itself
Solution Approach 2:
The patent performs alignment feature formation during the photonic circuit fabrication process rather than during final packaging. Alignment waveguides are pre-formed with visible alignment features and correct positioning before the device is packaged. This preliminary creation of alignment structures eliminates the need for expensive active alignment equipment and procedures, reducing overall device cost while maintaining alignment capability
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
Enables accurate and efficient alignment of PICs with external components, overcoming the limitations of traditional alignment methods and facilitating the use of edge couplers for wider bandwidth applications.
Implementation Method 1
a device coupler configured to receive light and couple the light to the waveguide to illuminate the waveguide
Data Source
AI summary
The present disclosure is directed towards aligning a photonic integrated circuit (PIC) through providing a PIC with a marker waveguide, wherein a marker waveguide is a waveguide having: a first end located at the edge of the PIC wherein the first end is coupled to an edge coupling; and a second end coupled to a grating coupler or a device coupler, wherein: the grating coupler or device coupler is configured to receive light and couple the light to the waveguide to illuminate the waveguide to facilitate the correct alignment of the edge coupler to an external component.