Grating Coupler With Inclined Emission Surface
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Solution Overview
Problem
The existing grating coupler structures face limitations in mounting flexibility due to the optical fiber being a spatial obstacle when metal wires or other chips are present on the optical circuit, restricting component placement.
Innovation Solution
A grating coupler with an inclined emission end surface, allowing diffracted light to be emitted from the substrate, which enables flexible mounting by avoiding the need for the optical fiber to be positioned on the upper surface of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical fiber is arranged on the upper surface of the substrate to couple with diffracted light, then coupling efficiency is improved, but mounting flexibility deteriorates due to spatial obstacles
Solution Approach 1:
The invention changes the spatial arrangement from a planar configuration (optical fiber on upper surface) to a three-dimensional configuration (optical fiber at inclined angle). By inclining the emission end surface at a specific angle, the diffracted light exits at an angle rather than perpendicular to the substrate, allowing the optical fiber to be positioned in a different spatial plane and avoid obstacles on the upper surface while maintaining coupling efficiency
2Reliability
If a lens is used to adapt beam size to mode size, then coupling efficiency is improved, but device complexity increases
Solution Approach 1:
The invention extracts and removes the lens component from the optical coupling system. By designing the diffraction grating with a specific pitch and inclining the emission end surface, the system achieves beam size adaptation and mode matching directly through the grating structure itself, eliminating the need for separate lens elements while maintaining high coupling efficiency
3Ease of manufacture
If the emission end surface is perpendicular to the upper surface, then manufacturing is simplified, but mounting flexibility deteriorates
Solution Approach 1:
The invention changes the geometric parameter of the emission end surface from perpendicular (0 degrees) to inclined (specific angle). This parameter change enables the diffracted light to exit at an angle, providing spatial flexibility for component mounting while the inclination angle can be optimized to balance manufacturing complexity with mounting flexibility requirements
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 design enhances mounting flexibility by allowing the optical fiber to be positioned elsewhere, reducing spatial obstacles and enabling efficient coupling of diffracted light without using a lens, while maintaining high beam quality and focus adjustment capabilities.
Implementation Method 1
a diffraction grating is provided in a waveguide layer... diffracted light from the diffraction grating
Data Source
AI summary
A grating coupler according to the present disclosure includes a substrate that has a waveguide layer in which a diffraction grating is provided and a clad layer provided on the waveguide layer, wherein an emission end surface, of the substrate, from which diffracted light from the diffraction grating is to be emitted is inclined relatively to a direction perpendicular to an upper surface of the substrate.