Waveguide Grating Refractive Index Infusion for AR Coupling
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Solution Overview
Problem
Conventional near-eye displays (NEDs) face challenges in achieving high in- and out-coupling efficiencies of image light due to their low refractive index, which limits their performance in augmented reality systems requiring compactness, light weight, and a wide field-of-vision.
Innovation Solution
A manufacturing system that creates optical gratings with adjustable refractive indices through a combination of patterning, infusion, and post-processing, allowing for both uniform and non-uniform refractive index distributions, using reactive and non-reactive moieties and ion implantation to enhance light coupling and decoupling efficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used in near-eye displays, then the device can be manufactured with standard processes, but the refractive index remains low resulting in poor light coupling efficiency
Solution Approach 1:
The patent applies preliminary action by first forming the grating structure using standard photolithography processes, then subsequently infusing the high refractive index material into the pre-formed gratings. This two-step approach allows the grating pattern to be established before material infusion, enabling high coupling efficiency while maintaining compatibility with conventional manufacturing workflows.
Solution Approach 2:
The patent employs composite materials by combining conventional waveguide materials with high refractive index materials (such as titanium dioxide, hafnium oxide, or zirconium oxide) infused into the grating regions. This composite approach allows the waveguide to maintain its base structural properties while gaining enhanced light coupling capabilities from the high refractive index infusate.
2Reliability
If the refractive index is increased to improve coupling efficiency, then light coupling performance improves, but the manufacturing process becomes more complex requiring additional infusion steps
Solution Approach 1:
The patent merges multiple functions into the infusion step by simultaneously achieving refractive index enhancement, grating definition, and material deposition in a single infusion process. The infusion step serves both to increase the refractive index and to complete the grating formation, reducing the need for separate processing steps.
Solution Approach 2:
The patent utilizes parameter changes by controlling the infusion process conditions (temperature, pressure, time, and infusate concentration) to precisely tune the final refractive index of the gratings. By adjusting these parameters, the manufacturing process can achieve desired optical performance without requiring additional process steps.
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 system increases the refractive index of optical gratings from 1.7 to 4.0, thereby improving the in- and out-coupling efficiencies of light, enabling more effective image light guidance and projection in near-eye displays.
Implementation Method 1
the infusion system and the post-processing system introduce moieties into the optical gratings and cause chemical reactions thereby to change the material of which the optical gratings are composed
Implementation Method 2
The optical waveguide element is a structure that confines image light internally within the optical waveguide element
Implementation Method 3
The optical gratings are used to couple light into an optical waveguide element and/or decouple light from the optical waveguide element
Data Source
AI summary
A manufacturing system for creating waveguides that include optical gratings having high coupling efficiencies is described herein. The waveguides are used to guide image light from a source assembly to an eye of a user. The optical gratings are used to couple light into an optical waveguide element and/or decouple light from the optical waveguide element. The manufacturing system creates optical gratings by patterning and adjusts refractive indexes of the optical gratings by infusion and post-processing. A refractive index of an optical grating can be uniform or non-uniform. In-coupling efficiencies of light into a waveguide via the optical gratings and/or out-coupling efficiencies of light out of a waveguide via the optical gratings can be increased. The manufacturing system includes a patterning system, an infusion system, and a post-processing system.