Fresnel Mirror Waveguide for Uniform Light Extraction
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Solution Overview
Problem
Existing methods for extracting light from polymer optical waveguides are inefficient in achieving uniform light radiation, particularly for applications like liquid crystal display backlighting, where consistent illumination is crucial.
Innovation Solution
The use of a plurality of mirrors with specific refractive indices and configurations, including Fresnel mirrors and claddings, to couple light out of the waveguide perpendicular to its propagation direction, forming a uniformly radiating surface by adjusting the refractive indices and spacing of the mirrors, and optionally incorporating an endpoint reflector for increased light radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional planar fabrication methods are used with standard refractive index differences, then the waveguide structure is simple to manufacture, but light extraction efficiency is insufficient
Solution Approach 1:
The patent introduces a Fresnel mirror structure with specific refractive index parameters (n1=1.46 for silica, n2=1.71 for TiO2, n3=1.50 for SiOxNy) to optimize light extraction. By carefully selecting and arranging materials with different refractive indices in a multi-layer configuration, the system achieves enhanced light coupling out of the waveguide while maintaining compatibility with standard fabrication processes
Solution Approach 2:
The patent employs a composite structure combining multiple materials with different optical properties: silica base layer, TiO2 high-index layer, SiOxNy cladding layer, and aluminum reflective layer. This composite approach creates a Fresnel mirror that efficiently extracts light from the waveguide core while maintaining structural integrity and manufacturability
2Illumination intensity
If uniform light distribution is achieved through multiple mirrors and claddings, then illumination quality improves, but device complexity increases
Solution Approach 1:
The patent divides the light extraction function into multiple discrete mirror elements arranged in an array configuration. Each mirror segment (with dimensions such as 100μm x 100μm individual elements) independently contributes to light extraction, and their collective arrangement creates uniform illumination across the display area. This segmentation allows optimization of each element while achieving global uniformity
Solution Approach 2:
The patent implements spatially varying mirror densities and orientations to achieve uniform light distribution across different regions of the display. By adjusting the local concentration and angular orientation of mirror elements in different zones, the system compensates for non-uniform light propagation characteristics, ensuring consistent illumination quality throughout the viewing area
3Loss of energy
If refractive index differences are optimized for light extraction, then coupling efficiency improves, but material selection and fabrication precision requirements increase
Solution Approach 1:
The patent introduces a SiOxNy intermediate cladding layer with refractive index n3=1.50 that mediates between the high-index TiO2 mirror layer (n2=1.71) and the low-index silica waveguide core (n1=1.46). This intermediary layer provides a gradual refractive index transition, reducing reflection losses and improving light coupling efficiency while being compatible with standard PECVD fabrication processes that can precisely control its deposition
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 enables the formation of a uniformly radiating surface, improving light distribution and intensity across the waveguide, enhancing illumination in applications such as liquid crystal displays by efficiently coupling light out of the waveguide while maintaining sufficient light propagation.
Implementation Method 1
The first and second reflective ends reflect and transmit light
Implementation Method 2
The plurality of mirrors comprises at least one first material having at least one first refractive index, and the plurality of mirrors has an axis line. The plurality of mirrors comprises a first cladding comprising a second material having a second refractive index.
Implementation Method 3
The optical waveguide device comprises a Fresnel mirror comprising a plurality of mirrors, wherein at least one mirror comprises a first reflective end, and a second reflective end
Data Source
AI summary
An optical waveguide device comprises a plurality of mirrors, wherein at least one mirror comprises a first and second reflective end that reflect and transmit light. The plurality of mirrors comprises at least one first material having at least one first refractive index; an axis line; a first cladding comprising a second material having a second refractive index; a second cladding, formed above the first, comprising a third material having a third refractive index; a core comprising a fourth material; and a plurality of core parts formed within at least one of the first or second claddings. The fourth material has a fourth refractive index that is greater than the second and third refractive indices and the core parts have a plurality of core part ends coupled to one of the reflective ends where at least one core part end is approximately parallel to one of the reflective ends.