Surface-Coupled Laser Interposer for Passive Silicon Photonics Alignment
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Solution Overview
Problem
Coupling light from single mode edge emitting lasers to silicon photonics is costly and requires precise alignment, often necessitating active alignment due to tight tolerances of less than 0.5 micrometers, which complicates packaging and increases costs.
Innovation Solution
The use of surface coupled systems that eliminate the need for lenses by employing a surface coupled edge emitting laser with a first and second surface grating to couple light directly to a silicon photonics chip, allowing for passive alignment with tolerances increased to 1-2 micrometers or more, and incorporating an optical isolator to reduce back reflection and improve coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two lenses and a large isolator block are used to couple light from single mode edge emitting lasers to silicon photonics, then coupling efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes lenses from the optical coupling system, extracting only the essential components (isolator and direct coupling interface) while eliminating unnecessary elements. This extraction principle reduces device complexity and cost while maintaining coupling efficiency through direct laser-to-chip coupling geometry.
Solution Approach 2:
The patent introduces an isolator block as an intermediary component positioned between the laser and silicon photonics chip. This intermediary serves multiple functions: isolating back-reflected light from the laser while providing a stable mounting structure for direct coupling, thereby simplifying the overall system compared to traditional lens-based approaches.
2Reliability
If two lenses and a large isolator block are used to couple light from single mode edge emitting lasers to silicon photonics, then coupling efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The patent eliminates lenses from the optical coupling system, extracting only the essential isolator block and direct coupling interface. This removal of expensive optical components significantly reduces manufacturing cost while maintaining coupling efficiency through precise direct coupling geometry and isolator-based light management.
Solution Approach 2:
The patent employs a simpler isolator block structure that can be manufactured more economically compared to precision lens assemblies. The isolator serves as a cost-effective solution that provides both optical isolation and mechanical mounting functions, reducing overall system cost.
3Manufacturing precision
If active alignment is used to meet alignment tolerances of less than 0.5 micrometers, then alignment precision is improved, but packaging complexity and time increase
Solution Approach 1:
The patent employs passive alignment features where the isolator block and laser mounting structure provide self-aligning geometries. The direct coupling interface is designed with built-in alignment references that enable automatic positioning without active feedback control, thereby simplifying packaging while maintaining sub-micrometer alignment precision.
Solution Approach 2:
The patent incorporates pre-aligned mounting structures and isolator block geometries that establish alignment relationships before final assembly. By preparing alignment features in advance during manufacturing, the system achieves high precision without requiring complex active alignment procedures during packaging.
4Manufacturing precision
If active alignment is used to meet alignment tolerances of less than 0.5 micrometers, then alignment precision is improved, but packaging time increases
Solution Approach 1:
The patent uses passive alignment features with self-aligning geometries in the isolator block and mounting structures. These features enable automatic positioning during assembly without requiring time-consuming active feedback alignment procedures, thereby reducing packaging time while maintaining sub-micrometer precision.
Solution Approach 2:
The patent incorporates pre-established alignment references and pre-aligned mounting structures that are prepared during manufacturing. This preliminary preparation of alignment features eliminates the need for time-consuming active alignment procedures during final packaging, significantly reducing packaging time while maintaining high precision.
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 simplifies packaging, reduces costs, and enhances alignment tolerances, while also enabling wafer level testing and improving coupling efficiency by using surface gratings to expand the optical mode spot size and redirect light into silicon photonics waveguides with reduced back reflection and increased bandwidth.
Implementation Method 1
a surface coupled edge emitting laser with a first and second surface grating to couple light directly to a silicon photonics chip
Implementation Method 2
incorporating an optical isolator to reduce back reflection and improve coupling efficiency
Data Source
Figure 1
Figure 2A~2C
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AI summary
An example system includes a grating coupled laser, a laser optical interposer (LOI), an optical isolator, and a light redirector. The grating coupled laser includes a laser cavity and a transmit grating optically coupled to the laser cavity. The transmit grating is configured to diffract light emitted by the laser cavity out of the grating coupled laser. The LOI includes an LOI waveguide with an input end and an output end. The optical isolator is positioned between the surface coupled edge emitting laser and the LOI. The light redirector is positioned to redirect the light, after the light passes through the optical isolator, into the LOI waveguide of the LOI.