Silicon Photonics Optical Coupling Module with Intermediate Refractive Index
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Solution Overview
Problem
Current optical coupling technologies for silicon photonics chips face challenges in achieving efficient optical coupling with single mode optical fibers due to the large refractive index difference between silicon cores and cladding materials, leading to signal loss and alignment issues, particularly with grating couplers being sensitive to wavelength and side couplers having small optical alignment tolerance.
Innovation Solution
An optical coupling module is developed with a grating formed on a silicon optical waveguide, incorporating a refractive element with an intermediate refractive index between the core and cladding, which allows for improved optical coupling efficiency by reducing refractive index differences and enhancing alignment tolerance, enabling efficient coupling with both internal and external optical fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a grating coupler is used for optical coupling, then optical alignment tolerance is improved, but wavelength sensitivity increases and package size becomes large
Solution Approach 1:
The patent introduces a cladding layer with intermediate refractive index between the silicon core and the outer cladding material. This intermediate cladding layer acts as a mediator that gradually transitions the refractive index, reducing the abrupt index change that causes wavelength sensitivity in conventional grating couplers. The intermediate layer enables broader wavelength operation while maintaining alignment tolerance.
Solution Approach 2:
The patent modifies the refractive index parameter by introducing an intermediate cladding layer with refractive index between that of the silicon core (n≈3.5) and the outer cladding (n≈1.4). This parameter change from abrupt to gradual index transition reduces wavelength sensitivity and allows for more compact package design while maintaining coupling efficiency.
2Loss of energy
If the refractive index difference between core and cladding is reduced, then optical coupling efficiency is improved, but the structural complexity increases
Solution Approach 1:
The patent segments the cladding structure into two distinct layers: an inner cladding layer with intermediate refractive index and an outer cladding layer with lower refractive index. This segmentation allows the intermediate layer to reduce optical signal loss by minimizing abrupt index changes, while the overall structure remains relatively simple and manufacturable.
3Adaptability or versatility
If a side coupler is used for optical coupling, then wavelength independence is achieved, but optical alignment tolerance becomes very small
Solution Approach 1:
The intermediate cladding layer serves as a mediator that enables side couplers to achieve both wavelength independence and improved alignment tolerance. By gradually transitioning the refractive index, the intermediate layer reduces the sensitivity to alignment errors while maintaining the wavelength-independent operation characteristic of side couplers.
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 solution increases optical coupling efficiency, minimizes the size of the optical coupling module, simplifies the manufacturing process, and reduces costs, facilitating broader applications in silicon photonics technology.
Implementation Method 1
achieve optical coupling by arranging a core that is to be optically coupled in parallel with an angle (θ) at which light output from the grating 11 is refracted
Implementation Method 2
a cladding covering the core and holding the light in the core through total internal reflection
Data Source
AI summary
An optical coupling module for a silicon photonics chip in which a grating is formed on an optical waveguide, and a material having an intermediate refractive index between refractive indexes of a core and a cladding for side surface optical coupling of the silicon photonics chip is provided. The optical coupling module which is optically coupled with an internal/external optical fiber comprises a core transmitting light, and a cladding covering the core and holding the light in the core through total internal reflection, wherein a grating is formed at one end of the core, and a refractive element is formed between the one end of the core and the cladding, has an intermediate refractive index between the refractive indexes of the core and the cladding, and is optically coupled with the internal/external optical fiber.