Piecewise Rolled Vector Gratings with Multiplexed Boundaries
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Solution Overview
Problem
Existing rolled K-vector (RKV) gratings face challenges in achieving wide angular bandwidth and high coupling efficiency due to gaps between grating regions caused by practical exposure limitations, leading to illumination artifacts and image nonuniformities.
Innovation Solution
The implementation of piecewise varying RKV (P-RKV) gratings with multiplexed boundary regions, where each grating section has a unique K-vector and is separated by a boundary region that includes both K-vectors, allowing for improved uniformity and reduced illumination artifacts through sequential or simultaneous exposure of holographic recording material layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional RKV gratings are fabricated using conventional exposure methods, then the grating regions can be formed, but gaps between grating regions occur causing illumination artifacts and image nonuniformities
Solution Approach 1:
The grating structure is divided into multiple grating sections (first grating section, second grating section, etc.) with distinct K-vectors, where each section is independently exposed and controlled. This segmentation allows precise control over the formation of each grating region and eliminates gaps between them by ensuring continuous coverage through the multiplexed boundary regions.
Solution Approach 2:
Different regions of the grating structure are assigned different K-vectors and exposure parameters. The boundary regions specifically contain both first and second K-vectors to ensure continuous illumination, while the interior grating sections have their respective unique K-vectors. This local differentiation of properties eliminates illumination artifacts while maintaining the desired grating functionality throughout the structure.
2Adaptability or versatility
If multiple grating regions with different K-vectors are created, then wide angular bandwidth is achieved, but gaps and nonuniformities occur at the boundaries between regions
Solution Approach 1:
The multiplexed boundary regions combine both the first and second K-vectors within the same physical region. This merging of multiple K-vector functionalities into a single boundary zone ensures continuous and uniform illumination across the transition between grating sections, eliminating gaps and nonuniformities while preserving the wide angular bandwidth provided by the different K-vectors.
Solution Approach 2:
The multiplexed boundary regions act as intermediary zones between grating sections with different K-vectors. These boundary regions mediate the transition by containing both K-vectors, ensuring smooth illumination continuity and eliminating the artifacts that would otherwise occur at the sharp boundaries between regions with different optical properties.
3Manufacturing precision
If sequential or simultaneous exposure methods are used for holographic recording, then multiplexed boundary regions can be formed, but fabrication complexity increases
Solution Approach 1:
The fabrication process uses periodic exposure actions where the holographic recording material is exposed in a systematic sequence - first to form the first grating section and its boundary region, then subsequently exposed to form the second grating section. This periodic exposure methodology simplifies the complex task of forming multiplexed boundary regions by breaking it down into manageable, repeating exposure cycles that can be controlled and optimized.
Data Source
AI summary
Various embodiments of this disclosure relate to a piecewise varying rolled K-vector grating structure including: a first grating section containing a grating with a first K-vector, a second grating section containing a grating with a second K-vector; and a first boundary region positioned between the first grating section and the second grating section. The first boundary region is a multiplexed grating region including both the first K-vector and the second K-vector. Further disclosed is a method for recording such a grating structure utilizing a holographic recording process. Providing a multiplexed grating in the first boundary region may largely remove line exposure artifacts between adjacent sections of the P-RKV grating.