Etched facet coupling for flip-chip photonics bonding
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Solution Overview
Problem
Current flip-chip bonding technologies for integrating Indium Phosphide (InP) Semiconductor Optical Amplifiers (SOAs) with silicon photonics (SiP) chips face challenges such as reduced optical coupling efficiency due to angular emission and back-reflection, and alignment accuracy issues, which are exacerbated by the cleaving process and large facet distances.
Innovation Solution
The integration employs lithographically defined etched angled facets on both the InP-SOA and SiP chips to reduce phase tilt and back-reflection, with precise alignment using Z-stops and complementary etched facets, allowing for straight SOA waveguides and minimizing the gap between the chips, thereby enhancing optical coupling efficiency and alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cleaving process is used to form facets, then manufacturing simplicity is improved, but alignment accuracy and facet distance control deteriorate
Solution Approach 1:
The patent replaces the mechanical cleaving process with lithographically defined etched angled facets. This substitution allows for precise control of facet angles and positions through lithography and etching processes, eliminating the alignment accuracy and facet distance control issues associated with traditional mechanical cleving while maintaining manufacturing feasibility through standard semiconductor fabrication techniques.
Solution Approach 2:
The patent changes the formation method parameter from mechanical cleving to lithographic definition and etching. This parameter change enables precise control over facet angle, position, and distance, directly addressing the alignment accuracy deterioration caused by the traditional cleving process while preserving ease of manufacture through established semiconductor manufacturing techniques.
2Ease of operation
If large facet distance is used, then ease of assembly is improved, but optical coupling efficiency deteriorates
Solution Approach 1:
The patent changes the facet distance parameter from large to minimized through lithographically defined positioning. This allows the optoelectronic flip-chip to be placed at an optimized distance from the photonics chip facet, reducing optical coupling losses while maintaining ease of assembly through the structured guidance provided by the lithographically defined facets and alignment features.
Solution Approach 2:
The lithographically defined etched angled facets act as an intermediary structure that mediates between the need for easy assembly and optimal optical coupling. These precisely defined facets provide both mechanical guidance for assembly and optimal optical interfaces for coupling, eliminating the trade-off between assembly ease and coupling efficiency.
3Object-generated harmful factors
If angled facets are introduced, then back-reflection is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical facet formation processes with lithographically defined etched angled facets. This substitution achieves the back-reflection reduction benefit of angled facets while simplifying manufacturing by using standard lithography and etching techniques rather than complex mechanical processing, thereby reducing overall manufacturing complexity.
4Loss of energy
If phase tilt is reduced through angled facets, then optical coupling efficiency is improved, but alignment precision requirements increase
Solution Approach 1:
The lithographically defined etched angled facets serve as an intermediary structure that simultaneously addresses phase tilt reduction and alignment precision. By providing precisely defined angular surfaces through lithography, these facets correct phase tilt to improve optical coupling efficiency while the lithographic definition itself provides the alignment precision reference, eliminating the trade-off between these two requirements.
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 improves optical coupling efficiency and relaxes alignment tolerance, leading to better performance in multi-channel SOA integration by reducing back-reflection and phase tilt, and allowing for tighter integration with SiP chips, even with large on-chip gain requirements.
Implementation Method 1
the angled facets of the photonics chip are angled such that phase tilt due to angular emission to and from the optoelectronic flip-chip is reduced
Implementation Method 2
the angled facets of the optoelectronic flip-chip are angled away from a second plane perpendicular to the second one or more waveguides such that back-reflection within the optoelectronic flip-chip is reduced
Implementation Method 3
the first one or more waveguides are arranged to optically couple, across gaps between the photonics chip and the optoelectronic flip-chip, to respective second one or more waveguides
Data Source
AI summary
Disclosed are integrated photonics systems including a coupling strategy to couple light in and out of optoelectronic flip-chips bonded to a photonics chip. The refined tolerances for flip-chip assembly and angled facets defined on both chips at optical couplings improve optical performance.