Asymmetric Diffraction Grating for Brighter Optical Waveguides
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Solution Overview
Problem
Existing two-dimensional diffraction gratings in optical waveguides have limited shape adjustable parameters and low design freedom, which hinders efficient coupling-out efficiency and image brightness.
Innovation Solution
A diffraction grating with asymmetric micro-structure units, featuring edges that are not parallel to the dimension directions, allowing for adjustable parameters such as duty ratio, transformation angles, and edge positions, enhancing design freedom and coupling-out efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional two-dimensional diffraction gratings with regular micro-structure units are used, then the manufacturing process is simple, but the design freedom and coupling-out efficiency are limited
Solution Approach 1:
The patent applies asymmetry by designing micro-structure units with at least one asymmetric edge that is not parallel to either the first or second dimension directions. This asymmetric configuration breaks the symmetry of traditional regular micro-structure units, enabling adjustable diffraction characteristics and improved coupling-out efficiency while maintaining manufacturing feasibility through standardized fabrication processes
2Adaptability or versatility
If asymmetric micro-structure units with non-parallel edges are implemented, then the design freedom and coupling-out efficiency are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent implements local quality by introducing asymmetric edges only at specific locations of the micro-structure units rather than making the entire structure complex. The asymmetric edges are strategically positioned to provide the necessary design freedom and coupling-out efficiency, while the rest of the micro-structure units maintain simpler geometries that are easier to manufacture
Solution Approach 2:
The patent addresses structural complexity by considering the third dimension (depth/height) of the micro-structure units. The asymmetric edges are defined in the planar dimensions but their impact extends through the depth of the waveguide, allowing complex optical functionality to be achieved through relatively simple planar patterning that can be manufactured using standard semiconductor fabrication techniques
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 asymmetric structure improves diffraction selectivity, efficiency, and image brightness by providing more design flexibility and better pupil expansion.
Implementation Method 1
a diffraction grating is provided, which includes: a substrate; a plurality of micro-structure units formed on the substrate and periodically arranged at intervals in a first dimension direction and a second dimension direction
Data Source
AI summary
An diffraction grating comprises: a substrate; and a plurality of micro-structure units, which are formed on the substrate and are periodically arranged at intervals in a first dimension direction (p1) and a second dimension direction (p2). A pattern formed by the orthographic projections of the micro-structure units on the substrate comprises a first closed pattern, wherein the first closed pattern is an asymmetric pattern, the boundary of the first closed pattern is formed by sequentially connecting three or more edges in a surrounding manner, and among the three or more edges, there is at least one straight-line edge, which is neither parallel to the first dimension direction (p1) nor to the second dimension direction (p2).