Distributed Bragg Reflectors with Airgaps for Photonics
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Solution Overview
Problem
Photonics chips face limited coupling efficiency due to light leakage into the substrate, which is constrained by the refractive index contrast provided by buried oxide layers.
Innovation Solution
A distributed Bragg reflector is introduced between the optical component and the substrate, comprising alternating silicon layers and airgaps, enhancing index contrast and reducing light leakage by partial reflection at layer-airgap boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a buried oxide layer is used to reduce light leakage, then light leakage is reduced, but the reduction is limited by the refractive index contrast
Solution Approach 1:
The buried oxide layer is segmented into multiple thin oxide layers separated by airgaps, creating a distributed Bragg reflector structure. This segmentation increases the effective refractive index contrast and enhances light reflection, thereby reducing light leakage and improving coupling efficiency beyond what a single continuous oxide layer can achieve.
Solution Approach 2:
The buried oxide layer is transformed into a porous-like structure with airgaps distributed throughout. This airgap-containing structure provides higher refractive index contrast compared to solid oxide, enabling superior light reflection and reduced light leakage while maintaining the electrical isolation function.
2Loss of energy
If the refractive index contrast is increased to reduce light leakage, then light leakage is reduced, but the structural complexity increases
Solution Approach 1:
The oxide layer is divided into multiple periodic segments (thin oxide layers separated by airgaps) to create a distributed Bragg reflector. This segmentation achieves high refractive index contrast through the alternating structure rather than requiring a single thick layer, thereby reducing light leakage while maintaining manageable structural complexity through periodicity.
Solution Approach 2:
The buried oxide layer is structured with periodic alternation of thin oxide layers and airgaps, forming a distributed Bragg reflector. This periodic structure enables enhanced light reflection through constructive interference of reflected waves, achieving superior light leakage reduction with a systematic and manufacturable pattern rather than random complexity.
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 solution significantly reduces light loss to the substrate, improving coupling efficiency and optical bandwidth by increasing index contrast and enhancing light reflection.
Implementation Method 1
enhancing index contrast and reducing light leakage by partial reflection at layer-airgap boundaries
Implementation Method 2
a distributed Bragg reflector positioned between the optical component and the substrate. The distributed Bragg reflector includes a plurality of airgaps and a plurality of silicon layers that alternate in a vertical direction
Data Source
AI summary
Structures that include a distributed Bragg reflector and methods of fabricating a structure that includes a distributed Bragg reflector. The structure includes a substrate, an optical component, and a distributed Bragg reflector positioned between the optical component and the substrate. The distributed Bragg reflector includes airgaps and silicon layers that alternate in a vertical direction with the airgaps to define a plurality of periods.