Optical Waveguide Connection Structure with Bonding Layer Lens
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Solution Overview
Problem
The mode field of light emitted from silicon waveguides with tapered cores is not always converted into a plane wave suitable for coupling with optical fibers due to manufacturing errors, leading to degradation of coupling efficiency.
Innovation Solution
An optical waveguide connection structure with a bonding layer having a higher refractive index than the optical fiber's core, which fills the gap between the silicon waveguide and optical fiber, and features a recess on the optical fiber's end face, forming a lens structure to convert the mode field into a plane wave.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a tapered core waveguide is used to convert mode field diameter, then coupling efficiency between Si waveguide and optical fiber is improved, but manufacturing errors cause deviation from plane wave and degrade coupling efficiency
Solution Approach 1:
The patent introduces an optical converter as an intermediary component between the Si waveguide and optical fiber. This converter includes a first waveguide with tapered core for mode field diameter conversion and a second waveguide with curved core for mode field shape conversion to plane wave. The intermediary converter compensates for manufacturing errors and ensures reliable coupling despite variations in the tapered waveguide fabrication.
Solution Approach 2:
The optical converter is segmented into two distinct functional sections: a first waveguide portion with tapered core (for diameter conversion) and a second waveguide portion with curved core (for shape conversion). This segmentation allows each section to specialize in one aspect of mode field conversion, improving overall precision and reliability while making the system more robust to manufacturing variations in individual sections.
2Productivity
If Si waveguide is used for high integration and productivity, then optical component integration is improved, but coupling with optical fiber becomes difficult due to different mode fields
Solution Approach 1:
The optical converter serves as a mediator between the Si waveguide and optical fiber, bridging the mode field mismatch. The first waveguide with tapered core converts the mode field diameter, while the second waveguide with curved core converts the mode field shape to match the optical fiber, enabling efficient coupling while maintaining Si waveguide integration advantages.
Solution Approach 2:
The patent employs parameter changes in the waveguide structure - specifically varying the core dimensions along the propagation direction (tapered core) and introducing curvature (curved core) - to transform the mode field parameters from Si waveguide compatibility to optical fiber compatibility, achieving precise mode field matching.
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 configuration improves the coupling efficiency between silicon waveguides and optical fibers by ensuring the mode field plane is closer to a plane wave, enhancing the integration and productivity of optical components.
Implementation Method 1
the bonding layer has a refractive index greater than a refractive index of the second core of the second optical waveguide
Data Source
AI summary
An optical waveguide connection structure connects a Si waveguide and an optical fiber to each other with a bonding layer interposed therebetween. The Si waveguide has a core whose cross-sectional area in the direction perpendicular to the direction of propagation of light decreases toward the optical fiber, and a cladding that covers the core. The optical fiber has a fiber core, a fiber cladding that covers the fiber core, and a recess formed in an end face opposed to the Si waveguide. The bonding layer fills a gap between the end face of the Si waveguide and the end face of the optical fiber and the recess, and the bonding layer has a refractive index greater than the refractive index of the fiber core of the optical fiber.