Optical Device Spacer Refractive Index Gradient for Peripheral Pixel QE
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Solution Overview
Problem
In optical devices with a wave guide color filter (WGCF)-type structure, oblique light absorption by metal grids leads to a decrease in quantum effect (QE) especially for peripheral pixels, resulting in low optical efficiency.
Innovation Solution
The optical device incorporates a substrate with color filters and spacers of varying refractive indices, where the refractive index of the spacers decreases gradually from the central to the peripheral region, and the color filters' refractive indices differ significantly from the spacers, enhancing the numerical aperture (NA) without a microlens, thereby improving QE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a wave guide color filter structure is used instead of a microlens, then the device complexity is reduced, but the quantum effect of peripheral pixels deteriorates due to oblique light absorption by metal grids
Solution Approach 1:
The patent applies local quality by differentiating the refractive index characteristics of spacers based on their location. Central region spacers have a first refractive index while peripheral region spacers have a second refractive index that is lower, creating a gradient structure. This local differentiation optimizes light extraction for peripheral pixels without compromising the overall wave guide structure's simplicity.
Solution Approach 2:
The patent changes the refractive index parameter of the spacers to improve quantum effect. Specifically, it reduces the refractive index of spacers in the peripheral region compared to those in the central region. This parameter change enhances the numerical aperture and reduces oblique light absorption, thereby improving the quantum effect of peripheral pixels while maintaining the wave guide structure.
2Reliability
If the refractive index of spacers is reduced in peripheral regions, then the numerical aperture increases and quantum effect improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent segments the spacer structure into two distinct regions: a central region and a peripheral region. Each region is assigned a different refractive index value (first refractive index for central, second refractive index for peripheral). This segmentation allows independent optimization of each region's optical properties while simplifying the overall manufacturing process compared to implementing a continuous gradient.
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 effectively enhances the quantum effect of peripheral pixels by increasing the numerical aperture, improving optical efficiency for large-angle incident light without the need for a microlens.
Implementation Method 1
the difference between the refractive index of the second spacer and the refractive index of the second color filter is greater than the difference between the refractive index of the first spacer and the refractive index of the first color filter
Data Source
AI summary
An optical device is provided. The optical device includes a substrate, a plurality of color filters and a plurality of spacers. The substrate has a central region and a peripheral region. The plurality of color filters include red color filters, green color filters and blue color filters and are formed on the substrate. The plurality of spacers are formed between the color filters. The refractive index of the spacers reduces gradually from that of the spacer located at the central region to that of the spacer located at the peripheral region of the substrate.