Photonic Integrated Circuit Coupler for Interlayer Waveguide Transmission
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Solution Overview
Problem
In photonic integrated circuit (PIC) structures, achieving low-loss optical signal transmission between waveguides with large separation distances is challenging due to design constraints that limit the proximity of adjacent end portions, making it difficult to maintain optimal signal quality without exceeding maximum signal loss thresholds.
Innovation Solution
The implementation of a coupler with an array of photonic material elements or a photonic material layer, embedded in or surrounded by cladding material, facilitates low-loss optical signal transmission between waveguides by optimizing the shape, size, and arrangement of these elements to ensure effective mode matching and minimize signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the separation distance between adjacent end portions of waveguides is increased to satisfy design constraints, then the ease of manufacture and layout flexibility improve, but the optical signal transmission loss increases
Solution Approach 1:
A coupler structure comprising an array of photonic material elements (such as photonic crystal elements or photonic metamaterial elements) is introduced as an intermediary between the first end portion and the second end portion of the waveguides. This coupler facilitates optical signal transmission across the separation distance by providing intermediate coupling points, thereby reducing transmission loss while maintaining the required layout flexibility
Solution Approach 2:
The coupler utilizes vertical stacking of photonic material elements to create additional coupling pathways in the vertical dimension. This allows optical signals to couple between waveguides separated in the lateral direction by providing intermediate coupling layers at different heights, effectively reducing the impact of lateral separation distance on transmission loss
2Device complexity
If the separation distance between adjacent end portions of waveguides is increased, then the device complexity for avoiding overlap is reduced, but the optical signal transmission quality deteriorates
Solution Approach 1:
The coupler acts as a mediator that enables reliable optical signal transmission between waveguides that are physically separated. By introducing the array of photonic material elements as intermediate coupling structures, the system achieves good transmission quality without requiring the waveguides to be in close proximity or to have complex overlapping configurations
3Manufacturing precision
If the separation distance between adjacent end portions of waveguides is increased, then the manufacturing precision requirements for alignment are relaxed, but the signal loss increases
Solution Approach 1:
The coupler with its array of photonic material elements serves as an intermediary that compensates for the increased separation distance between waveguides. This intermediate structure provides multiple coupling points that maintain effective optical coupling even when the waveguides are farther apart, thereby reducing signal loss while allowing for relaxed alignment precision requirements
Solution Approach 2:
The coupler divides the coupling function into multiple discrete photonic material elements arranged in an array. This segmentation creates multiple intermediate coupling points between the waveguides, which collectively maintain effective optical coupling over larger separation distances, reducing the sensitivity to alignment precision
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 enables efficient interlayer waveguide coupling, reduces signal loss, and improves through-band performance by facilitating mode evolution and suppressing higher-order mode issues, while allowing for scalable PIC designs.
Implementation Method 1
The coupler can include an array of photonic material elements (e.g., photonic crystal elements or photonic metamaterial elements) between and physically separated from the first end portion and the second end portion
Implementation Method 2
The coupler can include an array of photonic material elements (e.g., photonic crystal elements or photonic metamaterial elements) between and physically separated from the first end portion and the second end portion
Data Source
AI summary
Disclosed is a photonic integrated circuit (PIC) structure including a first waveguide core with a first end portion, a second waveguide core with a second end portion overlaying and physically separated from the first end portion, and a coupler configured to facilitate low-loss optical signal transmission between the waveguide cores. The coupler can include at least one array of photonic material elements (e.g., photonic crystal elements or photonic metamaterial elements) embedded in cladding material between the end portions. Alternatively, the coupler can include at least one photonic material layer (e.g., a photonic crystal layer or a photonic metamaterial layer) between and physically separated from the end portions and an array of cladding material elements extending through the photonic material layer. Also disclosed is a PIC structure including an on-chip system (e.g., a photonic computing system) including a crossing array implemented using any of the above-described couplers.