Dual Core Waveguide for Lens-Free Optical Coupling
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Solution Overview
Problem
Current photonic integrated circuits face challenges in aligning optical fibers with waveguides due to size mismatch, requiring stringent alignment tolerances and lenses, which increases manufacturing costs and complexity.
Innovation Solution
A thick, planar dual core waveguide structure is developed using a stack of silicon oxynitride films with a lower core thickness-matched to optical fibers and an upper core for single mode propagation, allowing direct optical signal coupling without lenses and relaxed alignment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If optical fibers are directly coupled to waveguides, then alignment complexity is reduced, but size mismatch causes signal loss
Solution Approach 1:
The waveguide is segmented into two distinct cores: a first core with dimensions matched to optical fibers and a second core with dimensions optimized for waveguide propagation. This segmentation allows each core to perform its specialized function, enabling efficient coupling while maintaining low signal loss.
Solution Approach 2:
The first core acts as an intermediary structure between the optical fiber and the second core. It provides a transition zone that matches the impedance and dimensions between the fiber and the waveguide, facilitating efficient energy transfer without requiring complex alignment mechanisms.
2Manufacturing precision
If lenses are used to reduce spot size, then alignment tolerance is improved, but device complexity increases
Solution Approach 1:
The external lens component is extracted and replaced by an integrated first core within the waveguide structure. The first core's dimensions and refractive index are specifically designed to perform the focusing function that would otherwise require a separate lens, thereby maintaining alignment tolerance while reducing device complexity.
Solution Approach 2:
The coupling function and waveguide function are merged into a single dual-core structure. The first core handles both the coupling from the fiber and the initial focusing, while the second core handles the waveguide propagation, eliminating the need for separate lens components.
3Manufacturing precision
If polishing is performed on fiber terminations, then alignment precision is improved, but manufacturing cost increases
Solution Approach 1:
The dual-core waveguide structure provides self-aligning capabilities through its geometric design. The first core's dimensions are specifically matched to standard optical fiber specifications, creating a natural alignment reference that eliminates the need for costly polishing operations to achieve precise alignment.
4Area of moving object
If waveguide cross section is reduced, then integration density is improved, but alignment difficulty increases
Solution Approach 1:
The waveguide is segmented into two cores with different cross-sectional dimensions. The first core has larger dimensions that are easier to align with optical fibers, while the second core has smaller dimensions for high integration density. This segmentation allows the system to benefit from both large and small cross-sections in different functional regions.
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 dual core waveguide structure enables efficient optical signal coupling and processing with reduced signal loss and alignment complexity, facilitating cost-effective manufacturing of photonic integrated circuits.
Implementation Method 1
The thickness of the lower core is substantially matched to a core diameter of the optical fiber, and receives the optical signal from the optical fiber
Implementation Method 2
enables efficient optical signal coupling and processing with reduced signal loss
Data Source
AI summary
The invention described herein pertains to the structure and formation of dual core waveguide structures and to the formation of optical devices including spot size converters from these dual core waveguide structure for the receiving and routing of optical signals on substrates, interposers, and sub-mount assemblies.