Tapered Waveguide Spot Size Converter for Efficient Light Coupling
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Solution Overview
Problem
Existing spot size converters experience a decrease in light conversion efficiency due to weak coupling between waveguides, which limits their effectiveness.
Innovation Solution
A spot size converter design featuring a first waveguide with a first core layer and a second waveguide above it, both extending in a waveguide direction, where the second waveguide has a tapered shape with a cross-sectional width that narrows away from the first waveguide, and an angle between its side surface and bottom surface of 60° or less, enhancing light coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spot size converter with two waveguides is used, then the device structure is simple, but the coupling between waveguides is weak and conversion efficiency decreases
Solution Approach 1:
The patent changes the geometric parameters of the waveguide cross-section by introducing a tapered shape with a specific angle (60° or less). This parameter modification optimizes the mode field distribution and coupling characteristics between waveguides, thereby improving conversion efficiency without adding complex structural elements
Solution Approach 2:
The patent applies a tapered (curved/angled) cross-sectional shape to the waveguide instead of a conventional rectangular or circular shape. This curved/tapered geometry modifies the optical confinement and evanescent field distribution, enhancing the coupling between adjacent waveguides and improving light conversion efficiency
2Reliability
If the second waveguide has a tapered shape with angle 60° or less, then light conversion efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a quantitative parameter range (tapering angle of 60° or less) that balances optical performance and manufacturability. This parameter optimization ensures sufficient conversion efficiency while remaining compatible with standard semiconductor fabrication capabilities, avoiding excessively tight tolerances that would compromise manufacturing 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
The tapered design improves light conversion efficiency between the waveguides, maintaining mechanical strength while reducing the effective refractive index, thus enhancing the overall performance of the converter.
Implementation Method 1
a coupling between the waveguides is weak, and a conversion efficiency of the light may decrease
Data Source
AI summary
A spot size converter includes a first waveguide including a first core layer, the first waveguide propagating light; and a second waveguide including a second core layer and provided on the first waveguide, the second waveguide propagating light. The first waveguide and the second waveguide extend in a waveguide direction. A first region and a second region are provided continuously along the waveguide direction. In the first region, the second waveguide has a tapered shape in a cross section which becomes narrower as going up away from the first waveguide. An angle between a side surface of the second waveguide and a bottom surface of the second waveguide is 60° or less.