Bragg Polarization Grating Waveguide for Uniform Intensity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Optical waveguides used in near-eye or heads-up display systems often suffer from non-uniform intensity distributions due to multiple-loop interference and polarization inefficiencies, leading to undesirable dark and light fringes and blotches in the replicated images.

Innovation Solution

The implementation of an optical waveguide with an intermediate-component configured as a Bragg polarization grating, utilizing a stack of birefringent layers that diffracts light into specific circular polarization beams, optimizing diffractive efficiency for certain polarization angles and reducing interference loops to achieve a more uniform intensity distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional waveguide structures are used, then the device can guide light, but non-uniform intensity distributions occur due to multiple-loop interference and polarization inefficiencies

Engineering Contradiction:

Improveintensity distribution uniformityVSAvoidmultiple-loop interference and polarization inefficiencies

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and eliminates the harmful multiple-loop interference paths by designing a waveguide structure that allows only a single optical loop. This is achieved by strategically placing the input coupler, output coupler, and polarization grating to create a direct optical path without redundant reflections, thereby removing the source of interference and achieving uniform intensity distribution.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the polarization state parameter of light by incorporating a polarization grating that converts linearly polarized light from the input coupler into circularly polarized light. This parameter change ensures that the light maintains consistent polarization characteristics throughout the single optical loop, eliminating polarization-related intensity variations and achieving uniform output.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If traditional coupling methods are used, then light can be coupled into the waveguide, but polarization inefficiencies cause non-uniform intensity output

Engineering Contradiction:

Improvelight intensity uniformityVSAvoidpolarization control complexity

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent introduces a polarization grating as an intermediary component between the input coupler and output coupler. This grating acts as a mediator that systematically controls the polarization state of light, converting linear polarization to circular polarization in a controlled manner. This intermediary element simplifies the overall polarization control mechanism while achieving uniform intensity distribution through the managed polarization transformation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration enhances the uniformity of light intensity output, making the replicated images appear more consistent and reducing noticeable fringes and blotches, thereby improving the overall image quality in near-eye or heads-up display systems.

Implementation Method 1

the intermediate-component is implemented as a Bragg polarization grating that comprises a stack of birefringent layers that is configured to diffract the light corresponding to the image that is incident thereon into a zero-order beam having one of right handed circular polarization or left handed circular polarization, and a first-order beam having the other one of right handed circular polarization or left handed circular polarization

Methodology Applied

Scientific EffectBragg diffraction: Bragg Diffraction

Implementation Method 2

a Bragg polarization grating that comprises a stack of birefringent layers

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 3

The output-coupler is configured to couple, out of the optical waveguide, the light corresponding to the image that travels in the optical waveguide from the input-coupler to the output-coupler via the intermediate-component by way of total internal reflection (TIR)

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS10095045B2Waveguide comprising a bragg polarization grating

Publication Date: 2018.10.09 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

An optical waveguide, for use a near-eye or heads-up display system, includes an input-coupler, an intermediate-component and an output-coupler. The input-coupler is configured to couple light corresponding to an image that is incident on the input-coupler, into the optical waveguide and towards the intermediate-component. The intermediate-component can be implemented as a Bragg polarization grating that comprises a stack of birefringent layers configured to diffract the light corresponding to the image that is incident thereon into a zero-order beam having one of right handed circular polarization or left handed circular polarization, and a first-order beam having the other one of right handed circular polarization or left handed circular polarization. The output-coupler is configured to couple, out of the optical waveguide, the light corresponding to the image that travels in the optical waveguide from the input-coupler to the output-coupler via the intermediate-component by way of total internal reflection (TIR).