Graded-Index Waveguide Gratings With Atmospheric Plasma Tuning
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Solution Overview
Problem
Conventional methods for forming waveguides in augmented reality devices face challenges in reducing signal loss and achieving sufficient clarity, requiring multiple process steps and chambers, which increase production costs and decrease yield.
Innovation Solution
A method and apparatus that form multi-dimensional recess features with a graduated refractive index by expelling plasma from an applicator at atmospheric pressure to change the depth and refractive index of grating structures, allowing for precise control of grating depth and refractive index across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional approaches alter thickness of gratings or encapsulation layer to tune optical characteristics, then optical performance is improved, but device complexity and manufacturing complexity increase due to multiple process steps and chambers
Solution Approach 1:
The patent combines multiple process steps (grating formation, thickness adjustment, optical tuning) into a single integrated process chamber, eliminating the need for multiple separate chambers and reducing manufacturing complexity while maintaining optical performance
Solution Approach 2:
The encapsulation layer serves multiple functions simultaneously: it provides structural support, protects the grating structures, and acts as a refractive index modulation layer for optical tuning, eliminating the need for separate dedicated layers for each function
2Manufacturing precision
If conventional approaches use multiple process chambers to achieve desired optical performance, then manufacturing precision is improved, but productivity decreases and production costs increase
Solution Approach 1:
Multiple process chambers are merged into a single integrated chamber that can perform grating formation, thickness control, and optical tuning in sequence, thereby increasing production throughput and yield while maintaining precision
Solution Approach 2:
The encapsulation layer is formed with predetermined thickness and refractive index characteristics in advance, allowing subsequent optical tuning to be performed more efficiently with fewer adjustment steps
3Manufacturing precision
If grating depth is increased to improve diffraction efficiency, then optical performance is improved, but signal loss increases due to visual defects
Solution Approach 1:
The encapsulation layer is applied with spatially varying thickness or refractive index across different regions of the grating structure, allowing local optimization of diffraction efficiency while compensating for signal loss in specific areas
Solution Approach 2:
The refractive index of the encapsulation layer is precisely controlled and varied to optimize the balance between diffraction efficiency and signal loss, achieving better overall optical performance than grating depth alone
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 approach enhances diffraction efficiency and reduces visual defects, achieving a uniform light profile and increased viewing angle with fewer processing steps, thereby improving the clarity and efficiency of augmented reality displays.
Implementation Method 1
expelling plasma from an applicator having a head toward the plurality of grating structures. The plasma is formed in the head at atmospheric pressure
Implementation Method 2
changing a depth of the plurality of grating structures with the plasma by removing grating material from the plurality of grating structures
Implementation Method 3
The waveguide includes multiple device structures, e.g., gratings. Generated light is propagated through a waveguide until the light exits the waveguide and is overlayed on the ambient environment
Data Source
AI summary
The present disclosure generally relates to a method and apparatus for forming a substrate having a graduated refractive index. A method of forming a waveguide structure includes expelling plasma from an applicator having a head toward a plurality of grating structures formed on a substrate. The plasma is formed in the head at atmospheric pressure. The method further includes changing a depth of the plurality of grating structures with the plasma by removing grating material from the plurality of grating structures.