Hybrid III-V on SOI Laser Source with Tapered Ridge Structures
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Solution Overview
Problem
Current laser sources for photonic integrated circuits on silicon face challenges in efficiently generating and coupling light between III-V and silicon on insulator materials, with existing solutions being sensitive to bonding defects and experiencing poor thermal behavior or high optical losses due to deep etching and rough sidewalls.
Innovation Solution
A hybrid laser source with a shallow ridge structure for light amplification and a deep ridge structure for efficient mode coupling between III-V and SOI waveguides, featuring tapered sections for adiabatic mode transfer and reduced sensitivity to bonding quality, along with a bonding layer for improved thermal behavior and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep ridge structure is used for mode coupling, then coupling efficiency is improved, but optical losses increase due to light scattering by rough etched sidewalls
Solution Approach 1:
The patent applies different ridge depths to different functional regions: shallow ridge structure in the active waveguide region to minimize optical losses, and deep ridge structure in the tapered coupling regions to maximize mode coupling efficiency. This local differentiation resolves the contradiction by optimizing each region for its specific function.
2Reliability
If a deep ridge structure is used for mode coupling, then coupling efficiency is improved, but device robustness and reliability decrease
Solution Approach 1:
The patent uses shallow ridge structure in the active waveguide region where mechanical strength is critical, and deep ridge structure only in the tapered coupling regions where coupling efficiency is paramount. This spatial differentiation maintains overall device robustness while achieving effective coupling.
3Reliability
If the distance between III-V active layer and silicon waveguide is increased with a bonding layer, then sensitivity to bonding defects is reduced, but mode coupling efficiency decreases
Solution Approach 1:
The patent transitions from lateral mode coupling (in the same plane) to vertical mode coupling through tapered regions that extend the interaction length in the longitudinal dimension. This allows efficient coupling despite the presence of a bonding layer and larger vertical separation.
Solution Approach 2:
The tapered waveguide regions act as intermediary structures that gradually transform the optical mode from the III-V waveguide to the silicon waveguide, enabling efficient coupling across the bonding layer interface through adiabatic transformation.
4Loss of energy
If closely stacked waveguide layers are used, then mode overlapping is improved, but sensitivity to bonding defects increases
Solution Approach 1:
The patent uses tapered regions that extend the coupling interaction along the longitudinal dimension, compensating for the reduced vertical overlap caused by the bonding layer. This allows maintaining coupling efficiency while accepting larger vertical separation.
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 hybrid laser source achieves high coupling efficiency and reliability, reducing sensitivity to bonding defects and improving thermal behavior, while maintaining robustness and power efficiency, making it suitable for photonic integrated circuits.
Implementation Method 1
tapered sections for adiabatic mode transfer
Implementation Method 2
the light amplification takes place inside the III-V material
Implementation Method 3
bonding layer for improved thermal behavior
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a laser source, and more especially a laser source for photonic integrated devices. Its object is a laser source of the III-V type bonded onto a SOI type material (8) that is substantially not sensitive to the bonding quality, that has good thermal behaviour and that does not require deep etching of the III-V waveguide. According to the invention, this laser source comprises one central waveguide (8) formed in an etched III-V die and coupled to two end waveguides formed in a SOI -type die, these dies being bonded together, and is characterized in that it comprises a shallow ridge structure (7) for the III-V straight waveguide region, and a deep ridge structure for the tapered region (20A,20B) for efficient mode coupling from III-V to SOI waveguides.