Silicon Photonic Coupler Tapers for Low-Loss Fiber Alignment
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Solution Overview
Problem
Existing photonic systems face challenges in achieving low insertion loss and low back reflection during optical coupling between silicon waveguides and standard single mode fibers, leading to high coupling loss and increased costs due to the use of additional components like refracting lenses and non-standard fiber diameters, which are not viable for high-volume manufacturing.
Innovation Solution
The implementation of low numerical aperture optical couplers with a lateral taper section and optional vertical adiabatic taper section, utilizing two or more silicon nitride layers, which are self-aligned to silicon V-grooves, allowing for passive alignment and reduced back reflection, and compatible with standard CMOS processes for high-volume manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refracting lenses and non-standard fiber diameters are used to achieve low insertion loss and low back reflection, then optical coupling performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for external refracting lenses and non-standard fiber components by integrating the optical coupling function directly into the silicon photonic waveguide structure through adiabatic taper design, thereby simplifying the overall system while maintaining low insertion loss and back reflection performance
Solution Approach 2:
The adiabatic taper waveguide structure performs self-alignment and self-coupling with standard single-mode fibers through its geometric design, eliminating the need for additional alignment mechanisms or specialized fiber components, enabling high-volume manufacturing with standard CMOS processes
2Loss of energy
If additional components like refracting lenses are added to reduce coupling loss, then optical coupling efficiency is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the optical coupling function with the waveguide structure itself by implementing adiabatic tapers that directly interface with standard single-mode fibers, eliminating the need for separate coupling components like refracting lenses and reducing overall device complexity while maintaining low coupling loss
Solution Approach 2:
The adiabatic taper acts as an intermediary structure that smoothly transitions the optical mode from the high-index-contrast silicon waveguide to the standard single-mode fiber, enabling efficient coupling without requiring additional components
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
This approach achieves low insertion loss and low back reflection over an extended wavelength range, enabling efficient optical coupling with standard single mode fibers, reducing fabrication costs and improving reliability through passive alignment.
Implementation Method 1
a vertical adiabatic taper section that extends from the front side of the first silicon nitride layer to the front side of the second silicon nitride layer
Implementation Method 2
a lateral taper section that extends from the front side of the first silicon nitride layer to the front side of the second silicon nitride layer
Data Source
AI summary
Embodiments of the present disclosure are directed to low numerical aperture (NA) optical couplers, or spot size converters, that include a lateral taper section and/or a vertical adiabatic taper section. In embodiments, the optical couplers may be positioned on a silicon substrate proximate to V-grooves within the substrate to contain optical fibers to self-align and to couple with the optical couplers. Other embodiments may be described and/or claimed.