Edge Coupler Layered Waveguide Structure for Reliable Fiber Coupling
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Solution Overview
Problem
The coupling of an optical fiber to a silicon photonic chip is hindered by mode spot size mismatch, leading to high coupling loss and structural unreliability in existing couplers, which are often suspended and prone to breakage during wafer dicing and chip packaging, increasing costs and process complexity.
Innovation Solution
A fabrication method for an edge coupler involving a semiconductor-on-insulator substrate, multiple dielectric layers, and a carrier substrate, with precise control over layer thickness and alignment to enhance coupling efficiency and structural reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If key parts of the coupler are in a suspended state to improve coupling efficiency, then coupling efficiency is improved, but structural reliability deteriorates and the parts are easily broken during wafer dicing and chip packaging
Solution Approach 1:
The patent introduces a sacrificial layer as an intermediary structure during fabrication. This sacrificial layer provides temporary support to the waveguide structure during wafer dicing and packaging processes, preventing structural failure. After the support function is no longer needed, the sacrificial layer is removed, leaving the final coupler structure. This mediator approach allows achieving both low coupling loss and structural reliability during manufacturing.
2Loss of energy
If multiple layers of materials are grown with precise control to improve coupling efficiency, then coupling efficiency is improved, but device complexity and process requirements increase
Solution Approach 1:
The patent divides the coupler structure into distinct functional segments: a first waveguide layer for optical transmission, a second waveguide layer for mode conversion, and a sacrificial layer for structural support during fabrication. This segmentation allows each layer to be optimized independently for its specific function, simplifying the overall design and manufacturing process while achieving low coupling loss through precise control of each individual layer.
3Loss of energy
If the first substrate is removed to improve access and coupling, then coupling efficiency is improved, but structural support is reduced
Solution Approach 1:
The patent performs preliminary action by bonding the waveguide structure to a carrier substrate before removing the original first substrate. This preliminary bonding ensures structural integrity is maintained throughout the substrate removal process and subsequent handling. The carrier substrate provides the necessary mechanical support after the original substrate is removed, allowing the coupler to achieve improved optical coupling while maintaining structural strength.
Data Source
AI summary
An edge coupler and a fabrication method therefor are provided. The method includes: providing a semiconductor-on-insulator substrate, the semiconductor-on-insulator substrate including a first substrate, an insulating layer on the first substrate, and a semiconductor layer on the insulating layer; patterning the semiconductor layer to form a first waveguide; forming a first dielectric layer on the insulating layer; forming a second dielectric layer on the first dielectric layer and the first waveguide; forming a second waveguide on the second dielectric layer; forming a third dielectric layer covering the second waveguide; bonding the third dielectric layer to a carrier substrate on a side of the third dielectric layer away from the second waveguide; removing the first substrate; and forming a fourth dielectric layer on a surface of the insulating layer.