Multilayer Photonic Adapter Mode Matching
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Solution Overview
Problem
SOI optical devices face challenges in efficiently transmitting optical signals due to the mismatch in mode field diameters between sub-micron waveguides and fiber optic cables, leading to low transmission efficiency and high coupling loss, and the constraints of fabricating waveguide adapters on the same layer as the waveguides, which are sensitive to temperature and materials used.
Innovation Solution
A multi-layer waveguide adapter is disposed above the silicon surface layer, with waveguides optically coupled to the silicon waveguide, forming an adiabatic structure to minimize mode coupling and improve signal transmission efficiency, allowing for the use of higher thermal temperatures for low-loss waveguides without damaging other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a waveguide adapter is fabricated on the same layer as the silicon waveguide, then the mode field diameter can be matched to fiber optic cables, but the fabrication process is constrained by temperature and material sensitivity of the silicon waveguide
Solution Approach 1:
The patent transitions from planar (2D) waveguide adapter fabrication to three-dimensional (3D) multi-layer stacking. The adapter is formed in layers above the silicon waveguide layer, with subsequent etching to create vertical waveguide structures. This dimensional change allows the adapter to be fabricated independently without temperature-sensitive processes affecting the underlying silicon waveguide, while still achieving mode field diameter matching to fiber optic cables.
2Loss of energy
If higher thermal temperatures are used for waveguide adapter fabrication, then low-loss waveguide performance is achieved, but other temperature-sensitive components on the silicon layer are damaged
Solution Approach 1:
The patent divides the waveguide structure into separate functional layers: the silicon waveguide layer containing temperature-sensitive components, and the adapter layer formed above it. This segmentation allows independent processing of each layer - the adapter layer can undergo high-temperature fabrication for low-loss performance, while the silicon waveguide layer remains protected from thermal damage.
3Ease of manufacture
If a multi-layer waveguide adapter is disposed above the silicon surface layer, then fabrication constraints are relaxed and low-loss operation is achieved, but device complexity increases
Solution Approach 1:
The multi-layer adapter structure serves multiple functions: it provides mode field diameter matching to fiber optic cables, enables low-loss waveguide operation through optimized fabrication, and acts as an optical interface between the silicon photonics circuit and external optical components. By consolidating these functions into a single multi-layer component, the overall device complexity is managed while achieving fabrication flexibility.
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 multi-layer adapter enhances optical signal transmission efficiency by matching the mode size of the waveguide to external optical components, simplifying fabrication and reducing manufacturing costs while maintaining low-loss operation.
Implementation Method 1
A multi-layer waveguide adapter is disposed above the silicon surface layer, with waveguides optically coupled to the silicon waveguide, forming an adiabatic structure to minimize mode coupling and improve signal transmission efficiency
Implementation Method 2
forming an adiabatic structure to minimize mode coupling and improve signal transmission efficiency
Data Source
AI summary
Embodiments herein describe disposing a waveguide adapter onto an SOI device after the components on a silicon surface layer have been formed. That is, the waveguide adapter is disposed above optical components (e.g., optical modulators, detectors, waveguides, etc) formed in a surface layer. In one embodiment, a waveguide in a bottom layer of the waveguide adapter overlaps a silicon waveguide in the surface layer such that the silicon waveguide and the waveguide in the bottom layer are optically coupled. The waveguide adapter also includes other layers above the bottom layer (e.g., middle and top layers) that also contain waveguides which form an adiabatic optical system for transmitting an optical signal. At least one of the waveguides in the multi-layer adapter is exposed at an optical interface of the SOI device, thereby permitting the SOI device to transmit optical signals to, or receive optical signals from, an external optical component.