Photonic Waveguide Membrane Structure for Reduced Substrate Losses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photonic circuits suffer from optical leakage and losses due to the overlap of light with the semiconductor substrate, leading to decreased output power and signal deterioration, particularly in quantum photonics applications, and current methods to increase the separation distance are costly, lack reproducibility, or introduce mechanical fragility.
Innovation Solution
A fabrication process involving a membrane structure formed by a stack of thermal and non-thermal SiO2 layers, which separates the optical guide structure from the semiconductor substrate, eliminating optical losses while maintaining mechanical robustness and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the thermal SiO2 layer is increased to eliminate optical coupling with the substrate, then optical losses are reduced, but the fabrication process becomes expensive and time-consuming due to thermal annealing requirements
Solution Approach 1:
The SiO2 layer is segmented into two distinct layers: a first thermal SiO2 layer (2-5 μm thick) providing optical isolation, and a second non-thermal SiO2 layer (1-3 μm thick) providing mechanical support. This segmentation allows each layer to be optimized for its specific function, eliminating the need for excessive thermal annealing of a single thick layer.
Solution Approach 2:
The patent uses a composite structure combining thermal SiO2 and non-thermal SiO2 layers. The thermal SiO2 provides excellent optical properties with low loss, while the non-thermal SiO2 provides mechanical strength. This composite approach achieves both optical isolation and structural integrity without the drawbacks of using only thermal SiO2.
2Loss of energy
If multiple thermal annealing cycles are performed to obtain a thick thermal SiO2 layer, then optical isolation is improved, but mechanical fragility increases
Solution Approach 1:
The SiO2 layer is segmented into two distinct layers: a first thermal SiO2 layer (2-5 μm thick) providing optical isolation, and a second non-thermal SiO2 layer (1-3 μm thick) providing mechanical support. This segmentation allows each layer to be optimized for its specific function, eliminating the need for excessive thermal annealing of a single thick layer.
Solution Approach 2:
The patent uses a composite structure combining thermal SiO2 and non-thermal SiO2 layers. The thermal SiO2 provides excellent optical properties with low loss, while the non-thermal SiO2 provides mechanical strength. This composite approach achieves both optical isolation and structural integrity without the drawbacks of using only thermal SiO2.
3Loss of energy
If the thickness of the SiO2 layer is increased to improve optical confinement, then light leakage is reduced, but the fabrication process lacks reproducibility
Solution Approach 1:
The SiO2 layer is segmented into two distinct layers: a first thermal SiO2 layer (2-5 μm thick) providing optical isolation, and a second non-thermal SiO2 layer (1-3 μm thick) providing mechanical support. This segmentation allows each layer to be optimized for its specific function, eliminating the need for excessive thermal annealing of a single thick layer.
Solution Approach 2:
The patent specifies precise thickness parameters for each layer: the thermal SiO2 layer is 2-5 μm and the non-thermal SiO2 layer is 1-3 μm. These controlled parameters ensure reproducible fabrication while achieving the desired optical confinement and mechanical properties.
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 process achieves reduced optical losses and improved confinement without resorting to costly thermal annealing, maintaining mechanical integrity and optical quality, enabling efficient quantum operations.
Implementation Method 1
thermal SiO2 is understood to mean a silicon dioxide layer formed by way of thermal oxidation of silicon wafers. This process consists in heating the silicon wafers in an oxygen-rich environment, thereby resulting in the formation of a thin surface layer of SiO2
Implementation Method 2
non-thermal SiO2 or deposited SiO2 is understood to mean a layer of silicon dioxide formed by way of deposition techniques such as plasma-enhanced chemical vapour deposition, sputtering or other deposition methods
Implementation Method 3
The optical guide structure WG0 is intended to confine an electromagnetic wave that is propagated along its direction of extension Y
Data Source
AI summary
A process for fabricating a photonic device, includes the following steps:(i) providing an optical guide structure arranged on a first thermal SiO2 layer; the first layer being arranged on a first face of a substrate made of a semiconductor material; (ii) etching the second face, opposite the first face, of the substrate below at least part of the optical guide structure to the first thermal SiO2 layer so as to obtain a membrane formed by part of the first layer that is suspended above a cavity delimited by two pillars; the optical guide structure being arranged on the membrane; (iii) depositing a second SiO2 layer on the first layer on the side of the cavity, so as to increase the thickness of the membrane.