Spot-Size Conversion Structure for Photonic Device Coupling
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Solution Overview
Problem
The existing coupling methods between integrated optical waveguides and optical fibers suffer from low coupling efficiency due to significant differences in spot size, leading to high light energy loss and reliability issues.
Innovation Solution
A spot-size conversion structure comprising a substrate, isolation layer, and waveguide layer with multiple sub-waveguide layers of varying widths and shapes, designed to gradually narrow from the integrated optical waveguide end to the optical fiber end, allowing for improved light transmission and reduced optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If edge coupling is used to connect integrated optical waveguide to optical fiber, then the coupling method is simple and widely applicable, but the coupling efficiency is low due to large spot size difference
Solution Approach 1:
The waveguide layer is divided into multiple sub-waveguide layers (first sub-waveguide layer, second sub-waveguide layer, third sub-waveguide layer, etc.) with progressively changing widths. Each sub-waveguide layer has a different width to gradually transform the spot size from the integrated optical waveguide scale to the optical fiber scale, thereby improving coupling efficiency while maintaining the simplicity of edge coupling
Solution Approach 2:
The invention introduces a vertical dimension by stacking multiple sub-waveguide layers at different heights above the substrate. The width of each sub-waveguide layer in the horizontal dimension is progressively reduced, while the vertical stacking provides additional degrees of freedom for spot size transformation, enabling efficient spot size conversion
2Reliability
If the width of sub-waveguide layers is gradually narrowed from first end face to second end face, then spot size transition is smoothed and coupling efficiency is improved, but the device complexity increases due to multiple layers with varying dimensions
Solution Approach 1:
The waveguide structure is segmented into multiple sub-waveguide layers, each with a specific width designed to progressively reduce the spot size. This segmentation allows the complex spot size transformation to be divided into multiple simpler steps, where each layer contributes to a portion of the overall transformation, making the design more manageable and manufacturable
Solution Approach 2:
The multiple sub-waveguide layers are arranged in a nested configuration where each layer is positioned at a different height above the substrate, with their horizontal projections overlapping. This nested arrangement allows the progressive width reduction to occur in a compact vertical space, reducing the overall device footprint while achieving the desired spot size transformation
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 proposed structure enhances coupling efficiency and reduces optical loss by allowing for a smoother spot transition and more precise design of sub-waveguide layers, leading to improved reliability and performance in photonic devices.
Implementation Method 1
an optical waveguide is a dielectric apparatus that guides the propagation of light waves therein
Data Source
AI summary
A spot-size conversion structure and a photonic device. The spot-size conversion structure includes: a substrate, an isolation layer and a waveguide layer arranged in sequence. The waveguide layer includes N sub-waveguide layers arranged in sequence along a direction away from the substrate, each of the sub-waveguide layers being of a protrusion shape, and N being a natural number and N≥3. Wherein, the spot-size conversion structure has a first end face configured to be coupled to an integrated optical waveguide, and a second end face opposite to the first end face and configured to be coupled to an optical fiber.