Edge Coupler Coupling-Assistance Features for Mode Transformation
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Solution Overview
Problem
Existing photonics chips face challenges in efficiently coupling light from a light source to a photonic integrated circuit using edge couplers, particularly in terms of mode transformation and mode size variation, leading to inefficiencies and polarization group delay.
Innovation Solution
The introduction of coupling-assistance features adjacent to the edge coupler, which are positioned laterally and embedded in a dielectric layer, to enhance mode transformation, reduce polarization group delay, and improve coupling efficiency by controlling mode size and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inverse taper edge coupler is used for mode transformation, then mode conversion is supported, but polarization group delay occurs and coupling efficiency is reduced
Solution Approach 1:
The edge coupler is divided into multiple sections: a first section with a first inverse taper, a second section with a second inverse taper, and intermediate sections with different cross-sectional areas. This segmentation allows different parts of the coupler to perform different functions, enabling mode transformation while reducing polarization group delay through optimized geometry in each section.
Solution Approach 2:
Different sections of the edge coupler are designed with different local geometries and cross-sectional areas. The first section has a different taper angle than the second section, and intermediate sections have varying cross-sectional areas. This local quality variation optimizes mode transformation at each stage while minimizing overall polarization group delay.
2Ease of manufacture
If a standard edge coupler structure is used, then fabrication is simplified, but coupling efficiency between light source and photonic integrated circuit is reduced
Solution Approach 1:
The edge coupler employs dynamic geometry variation along its length, with cross-sectional areas that change progressively from the input to the output. This dynamic structure, featuring multiple taper sections with different angles and intermediate sections with varying widths, optimizes coupling efficiency at each stage while remaining compatible with standard fabrication processes.
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 coupling-assistance features enhance the efficiency of light transfer from the light source to the photonic integrated circuit, reducing polarization group delay and improving mode transformation and size variation, thereby optimizing the coupling process.
Implementation Method 1
The gradually-varying cross-sectional area of the inverse taper supports mode transformation and mode size variation associated with mode conversion when light is transferred from the light source to the edge coupler
Implementation Method 2
The coupling-assistance features enhance the efficiency of light transfer from the light source to the photonic integrated circuit, reducing polarization group delay and improving mode transformation and size variation
Data Source
AI summary
Structures including an edge coupler and methods of forming such structures. The structure comprises an edge coupler including a first portion and a second portion between the first portion and a semiconductor substrate, a first coupling-assistance feature adjacent to the first portion of the edge coupler, and a second coupling-assistance feature adjacent to the first portion of the edge coupler. The first portion of the edge coupler is positioned in a lateral direction between the first coupling-assistance feature and the second coupling-assistance feature.