Layered Composite Edge Coupler for Photonic Chip Mode Adaptation
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Solution Overview
Problem
Existing edge couplers for photonic chips face challenges such as increased fabrication complexity, contamination issues, and limited design freedom due to buried waveguides, as well as difficulties in testing and managing polarization diversity, leading to higher costs and reduced production efficiency.
Innovation Solution
A photonic chip with a composite guiding structure comprising multiple parallel planar layers of optical guiding material, where the waveguide is deposited on the cladding material, allowing for efficient mode adaptation and reduced horizontal and vertical footprint, with a marker element for alignment, and a method of manufacturing that enables testing during fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buried waveguide structure is used in edge couplers, then mode adaptation between optical fibers and waveguides is achieved, but fabrication complexity increases and contamination issues arise
Solution Approach 1:
The waveguide is extracted from the buried structure and repositioned to the top surface of the photonic chip, allowing it to be deposited after the edge coupler is formed. This eliminates the contamination issues and fabrication complexity associated with buried waveguides while maintaining the mode adaptation function through the composite guiding structure at the chip edge.
Solution Approach 2:
The edge coupler and composite guiding structure are formed first, then the waveguide is deposited on the top surface. This preliminary action sequence allows the waveguide to be added without interfering with the edge coupler fabrication, reducing overall fabrication complexity while ensuring reliable mode adaptation.
2Reliability
If a buried waveguide structure is used, then light coupling is enabled, but design freedom is limited and testing becomes difficult
Solution Approach 1:
By extracting the waveguide from the buried position and placing it on the top surface, the design is freed from the constraints of buried structure fabrication. This allows greater design freedom in positioning other components and in the waveguide itself, while testing can be performed during fabrication rather than requiring post-fabrication access.
3Area of stationary object
If conventional edge coupler structures are used, then horizontal and vertical footprint is reduced, but fabrication complexity and contamination issues increase
Solution Approach 1:
The edge coupler and composite guiding structure are formed as a preliminary structure, then the waveguide is deposited on the top surface in a subsequent step. This sequence maintains the compact footprint while simplifying manufacturing by allowing the waveguide to be added after the edge coupler is already in place, eliminating the need for complex buried waveguide fabrication.
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
The solution provides a compact and efficient edge coupler structure that allows for greater design freedom, improved production yield, and efficient mode adaptation between optical fibers and waveguides, while reducing fabrication complexity and enabling testing throughout the process.
Implementation Method 1
Common techniques to perform the mode conversion include: i) tapering of the waveguide in combination with tapering of the fibre itself, ii) refractive index adaptation methods, such as subwavelength gratings and iii) evanescent coupling methods such as spot size converters and combinations thereof.
Implementation Method 2
Silicon photonic chips guide light through high and/or medium contrast index waveguides. Waveguides are generally formed of a core of higher refractive index material surround by a cladding fabricated from a lower refractive index material.
Data Source
AI summary
A photonic chip is disclosed that comprises a cladding material and an edge coupler. The edge coupler comprises a composite guiding structure that comprises a plurality of substantially parallel planar layers of optical guiding material. Each layer of the composite guiding structure extends into the cladding material, wherein each layer is aligned at a first edge of the photonic chip. The layers overlap along a first axis which is perpendicular to a plane of the planar layers of optical guiding material. The photonic chip is arranged for deposition of a waveguide on the cladding material, the waveguide being arranged to at least partially overlap along the first axis with a layer of the composite guiding structure.Also disclosed is a method of manufacturing a photonic chip.