Compact Waveguide Taper and Crossing for Photonic Integrated Circuits
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Solution Overview
Problem
Existing waveguide crossings in photonic integrated circuits occupy large chip areas and incur significant optical losses due to their design.
Innovation Solution
A tapered waveguide design with a narrow end and a wide end, featuring a taper angle within 30% of ΩL−α/ΩL, where ΩL=ρ/LB and ρ is half the width of the waveguide, and a taper shape parameter α between 0.1 and 0.4, is implemented, along with a crossing rectangle configuration that allows light to propagate between waveguides with reduced optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional waveguide crossing designs are used, then waveguide crossings can be implemented in photonic integrated circuits, but they occupy large chip areas and incur large optical losses
Solution Approach 1:
The patent applies parameter changes by optimizing the taper angle parameter (ΩL−α/ΩL where α is between 0.1 and 0.4) and the geometry of the crossing rectangle to simultaneously reduce both the area occupied and the optical loss. By changing the dimensional parameters of the waveguide taper and crossing structure, the invention achieves compact size while maintaining low optical loss transmission
Solution Approach 2:
The patent uses curved taper transitions instead of sharp angular changes in the waveguide geometry. The tapered waveguides employ smooth curved transitions with controlled taper angles, which reduce optical scattering and radiation losses while enabling more compact routing of the crossing structure
2Loss of energy
If conventional waveguide crossing designs are used, then waveguide crossings can be implemented in photonic integrated circuits, but they incur large optical losses
Solution Approach 1:
The patent optimizes the taper angle parameter (ΩL−α/ΩL where α is between 0.1 and 0.4) and the crossing rectangle dimensions to achieve low optical loss while minimizing the area occupied. This parameter optimization allows the crossing to fit in a compact footprint without sacrificing transmission efficiency
3Volume of moving object
If the tapered waveguide width is increased from 1.5 microns to 7 microns over a short distance, then the waveguide can accommodate the crossing structure, but the taper angle must be precisely controlled to maintain low optical loss
Solution Approach 1:
The patent defines a specific taper angle parameter ΩL−α/ΩL where α is between 0.1 and 0.4, which provides a precise design criterion for manufacturing. This parameterized approach translates the geometric requirement into a controllable manufacturing parameter, enabling precise fabrication of the taper transition
Solution Approach 2:
The patent applies different taper angle criteria at different locations along the waveguide. The taper angle is locally optimized at each point between the narrow and wide ends using the parameter ΩL−α/ΩL, which accounts for the local waveguide dimensions and ensures adiabatic transition conditions are met throughout the entire taper region
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 achieves optical losses of less than 0.08 dB and reduces the chip area occupied by waveguide crossings, while maintaining acceptable transmission and crosstalk levels.
Implementation Method 1
a tapered waveguide, having: a narrow end; and a wide end, the tapered waveguide having a taper angle, at each point between the narrow end and the wide end, within 30% of ΩL−α/ΩL, wherein: α is a positive constant, ΩL=ρ/LB
Implementation Method 2
β1 is a propagation constant, at the point, of a fundamental mode, and β2 is a propagation constant, at the point, of a higher order mode with a greatest overlap with the fundamental mode
Implementation Method 3
the crossing rectangle is configured to allow light to propagate from the first tapered waveguide to the third tapered waveguide, and to allow light to propagate from the second tapered waveguide to the fourth tapered waveguide
Implementation Method 4
β2 is a propagation constant, at the point, of a higher order mode with a greatest overlap with the fundamental mode
Data Source
AI summary
A tapered waveguide. In some embodiments, the waveguide has a narrow end and a wide end. A taper angle of the waveguide may be, at each point along the waveguide, less than an adiabatic taper angle by a margin. The margin may be greater at a first point than at a second point, where the adiabatic taper angle is less at the first point than at the second point.