Optical Mode-Size Converter Using Dielectric Strips
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Solution Overview
Problem
Existing photonic integrated circuits face challenges in achieving low-loss waveguide circuits, particularly in converting one optical mode to another with minimal transmission loss.
Innovation Solution
An optical mode-size converter is designed with a plurality of dielectric strips in a coupling layer and a waveguide in a functional layer, allowing for evanescent coupling to convert a larger optical mode into a smaller mode with low loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If direct coupling between waveguides of different mode sizes is used, then device complexity is reduced, but transmission loss increases due to mode mismatch
Solution Approach 1:
The mode converter is segmented into multiple discrete dielectric strips arranged in a specific pattern, rather than using a continuous or simple coupling structure. This segmentation allows gradual mode transformation while maintaining manageable device complexity
Solution Approach 2:
Multiple dielectric strips act as intermediary elements between the input and output waveguides, facilitating gradual mode transformation. These strips serve as intermediate structures that bridge the mode size mismatch, reducing transmission loss through step-by-step mode adaptation
2Loss of energy
If evanescent coupling regions are extended to improve mode conversion, then conversion efficiency increases, but device length increases
Solution Approach 1:
The dielectric strips are strategically positioned at specific locations within the converter where they provide the most effective mode transformation. Rather than uniformly distributing coupling elements throughout the entire length, the strips are placed where they locally maximize conversion efficiency while minimizing overall device length
Solution Approach 2:
The converter uses a limited number of dielectric strips (not a continuous distribution) to achieve effective mode conversion. This partial action approach provides sufficient coupling for low-loss conversion without requiring the full length that would be needed for more gradual or complete coupling structures
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 converter effectively minimizes power loss by gradually changing the mode profile from a larger to a smaller mode size, achieving efficient mode conversion with low coupling loss.
Implementation Method 1
the plurality of dielectric strips are coupled to each other in a first evanescent coupling region
Implementation Method 2
At least one of the plurality of dielectric strips is evanescently coupled to the first waveguide in a second evanescent coupling region
Data Source
AI summary
An optical mode-size converter is presented, which extends between a first plane to a second plane along a first path. The optical mode-size converter comprises: a plurality of dielectric strips within a coupling layer arranged to receive a beam with a first optical mode incident on the first plane, wherein the plurality of dielectric strips are coupled to each other in a first evanescent coupling region; and a first waveguide within a functional layer disposed above or below the coupling layer, the waveguide supporting a second optical mode and traversing the second plane. At least one of the plurality of dielectric strips is evanescently coupled to the first waveguide in a second evanescent coupling region. The first optical mode has a larger mode size than the second optical mode such that the converter is responsive to the first optical mode incident on the first plane to convert the first optical mode into the second optical mode in the first waveguide, along the first path towards the second plane.