Sloped Grating Coupler for Normal Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coupling optical signals between integrated circuit photonics devices and external optical fibers is challenging due to the small waveguide mode size, leading to significant optical signal power loss and complex mechanical and active alignment requirements.
Innovation Solution
A sloped grating coupler is designed and fabricated to direct light into or out of the photonic structure in a direction substantially normal to the upper surface, facilitating mechanical coupling with an optical fiber without the need for active alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional grating coupler is used to couple light between waveguide and optical fiber, then optical signal transmission is achieved, but significant optical signal power loss occurs due to the small waveguide mode size compared with optical fiber mode size
Solution Approach 1:
The patent introduces a sloped dimension to the grating coupler structure, transforming it from a planar surface to an inclined surface. This dimensional change allows the optical fiber to be positioned at an angle relative to the waveguide, improving mode field overlap and reducing coupling loss without requiring complex active alignment mechanisms
2Loss of energy
If a grating coupler is designed to direct light at an angle of 8-12 degrees from normal to the upper surface, then optical coupling efficiency is improved, but mechanical packaging complexity increases due to the need for angled fiber coupling
Solution Approach 1:
By incorporating a slope angle of 8-12 degrees into the grating coupler structure itself, the patent integrates the angular coupling requirement directly into the device geometry. This allows the optical fiber to be coupled at the optimal angle for efficiency while maintaining a relatively simple mechanical packaging structure, as the angle is built into the component rather than requiring complex alignment mechanisms
3Loss of energy
If precise optical alignment between optical fiber and photonic device is required to maximize optical signal transmission, then coupling efficiency is improved, but assembly complexity and cost increase due to active alignment requirements
Solution Approach 1:
The patent performs preliminary alignment by designing the grating coupler with a specific slope angle that pre-determines the optimal optical path. This preliminary geometric configuration ensures that when the optical fiber is positioned according to the designed angle, maximum coupling efficiency is achieved without requiring complex active alignment systems during assembly, thereby simplifying the manufacturing process
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 sloped grating coupler minimizes optical signal power loss and simplifies the assembly process by allowing for easy mechanical coupling with an optical fiber, reducing costs and complexity.
Implementation Method 1
Such optical coupling is made conventionally through a diffraction grating coupler provided on a planar upper surface of a waveguide which changes the direction of an optical signal passing through the waveguide
Data Source
AI summary
A structure for coupling an optical signal between an integrated circuit photonic structure and an external optical fiber is disclosed as in a method of formation. The coupling structure is sloped relative to a horizontal surface of the photonic structure such that light entering or leaving the photonic structure is substantially normal to its upper surface.