Bragg Grating Waveguide for Multi-Wavelength Artificial Reality
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Solution Overview
Problem
Artificial reality systems face challenges in reducing size, weight, and complexity due to the need for multiple waveguides and coupling gratings to manage different wavelengths of light effectively, leading to increased cost and manufacturing complexity.
Innovation Solution
The use of Bragg gratings with specifically selected refractive indices and layer pairs to achieve similar diffractive efficiencies and diffraction angles for multiple wavelengths, allowing a single waveguide to be used for multiple colors, thereby reducing the number of optical elements and simplifying alignment and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple waveguides and coupling gratings are used to manage different wavelengths of light, then optical performance is improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The patent applies universality by designing a single waveguide that can handle multiple wavelengths of light (red, green, blue) simultaneously, rather than requiring separate waveguides for each wavelength. The Bragg grating is configured with specific properties that enable it to couple multiple wavelengths into and out of the same waveguide, making the optical element universal across different color channels.
Solution Approach 2:
The patent employs parameter changes by carefully selecting the Bragg grating's physical parameters (period, depth, orientation) to achieve wavelength-independent coupling efficiency. By adjusting these parameters, the Bragg grating can effectively couple multiple wavelengths with similar diffractive efficiencies, allowing a single waveguide to maintain optical performance across different colors.
2Reliability
If multiple waveguides are used for different colors, then wavelength management is improved, but size and weight increase
Solution Approach 1:
The patent applies merging by combining the functions of multiple waveguides (designed for different wavelengths) into a single waveguide. The Bragg grating enables this consolidation by providing effective light coupling for multiple wavelengths within one waveguide structure, thereby reducing the overall weight of the artificial reality system while maintaining proper wavelength management.
3Reliability
If multiple waveguides and coupling gratings are used, then light coupling for different wavelengths is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent applies universality by creating a single waveguide-Bragg grating assembly that serves multiple wavelength channels, eliminating the need to manufacture and align multiple separate waveguide-grating pairs. This universal design significantly simplifies the manufacturing process while maintaining effective light coupling for red, green, and blue light.
4Device complexity
If a single waveguide is used for multiple colors, then device complexity is reduced, but optical performance may deteriorate
Solution Approach 1:
The patent employs parameter changes by optimizing the Bragg grating's physical characteristics (period, depth, orientation) to achieve wavelength-independent coupling. These parameter adjustments ensure that the single waveguide maintains similar diffractive efficiencies across multiple wavelengths, preserving optical performance despite the reduction in device complexity.
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 reduces the size, weight, and complexity of artificial reality systems while maintaining acceptable optical performance by enabling a single waveguide to handle multiple wavelengths with reduced image artifacts.
Implementation Method 1
Bragg gratings are described having properties selected so that the Bragg gratings have similar diffractive efficiencies and diffraction angles for a plurality of different wavelengths of light
Implementation Method 2
The Bragg gratings may be reflective or transmissive Bragg gratings
Implementation Method 3
the Bragg grating comprises a plurality of layer pairs, wherein at least one layer pair comprises a first material having a first refractive index and a second layer having a second refractive index
Data Source
AI summary
An optical assembly may include a waveguide and a Bragg grating configured to couple light into or out of the waveguide. The Bragg grating may include a plurality of layer pairs, wherein at least one layer pair comprises a first material having a first refractive index and a second layer having a second refractive index, and wherein properties of the Bragg grating are selected so that the Bragg grating exhibits a substantially similar diffractive efficiency and diffraction angle for light of at least two colors.