Pixelated Interference Filter Waveguides for Crosstalk Reduction
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Solution Overview
Problem
Existing pixelated filters with interference filters suffer from crosstalk issues due to light leakage between neighboring photosensitive elements, leading to reduced resolution, especially as the dimensions of photosensitive elements decrease and the number of interference filter layers increases.
Innovation Solution
Incorporating waveguides within each pixel of the pixelated filter that guide optical modes and interact with the interference filter layers, preventing coupling between neighboring pixels by configuring the waveguides to have a refractive index greater than the dielectric layers and maintaining a constant cross-section, which enhances light filtering and reduces crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of interference filter layers is increased to improve filtering characteristics, then the filtering efficiency is improved, but the total thickness of layers increases causing increased crosstalk
Solution Approach 1:
Waveguides are introduced as intermediary structures that channel light directly to photosensitive elements, mediating the interaction between incident light and the filter layers. The waveguides have evanescent portions that interact with the interference filter layers while guiding light through the stack, preventing direct light propagation through all layers and reducing crosstalk between neighboring pixels
Solution Approach 2:
The waveguide structure creates local optical confinement around each photosensitive element. By configuring waveguides with specific refractive indices greater than the dielectric layers and maintaining constant cross-sections, light is locally confined to interact primarily with the filter layers above each photosensitive element, reducing the harmful effect of light spreading to neighboring elements
2Measurement precision
If the dimensions of photosensitive elements are decreased to increase pixel density, then the resolution is improved, but the crosstalk between neighboring elements increases
Solution Approach 1:
Waveguides serve as intermediary light channels that become increasingly important as photosensitive elements shrink. The waveguides ensure that even as element dimensions decrease, light is still effectively channeled to the intended photosensitive element through evanescent field interaction with the filter layers, maintaining resolution while controlling crosstalk
Solution Approach 2:
The optical path is segmented into discrete waveguide channels, each serving a specific photosensitive element. This segmentation of the light propagation path ensures that light intended for one pixel remains confined to its designated waveguide, preventing interference with neighboring pixels even when element spacing is reduced
3Object-affected harmful factors
If waveguides are introduced to reduce crosstalk, then the crosstalk is reduced, but the device complexity increases
Solution Approach 1:
The waveguide structure merges multiple functions into a single component: light guidance, filter interaction, and pixel isolation are all achieved through the waveguide structure itself. The waveguides pass through the interference filter layers while guiding light, combining the filtering function with the light guidance function, thereby reducing overall device complexity despite the addition of waveguide elements
Solution Approach 2:
The waveguides serve multiple functions simultaneously: they guide optical modes to photosensitive elements, provide evanescent field interaction with interference filter layers for wavelength filtering, and act as optical isolation structures between neighboring pixels. This multi-functionality reduces the need for separate components, mitigating the increase 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
The solution significantly improves the filtering efficiency by reducing crosstalk, increasing transmission within the passband, enhancing rejection outside the passband, and expanding the angular tolerance of the filter, while maintaining or reducing crosstalk levels compared to reference designs.
Implementation Method 1
several waveguides (114) are provided in each pixel (Pix), each waveguide (114) passing through all or part of the layers (110A) of the interference filter (112) of this pixel (Pix). In each pixel (Pix), the waveguides (114) are configured to guide one or more optical modes and so that an evanescent portion of these guided modes is filtered by the interference filter (112) of this pixel (Pix)
Implementation Method 2
an evanescent portion of these guided modes is filtered by the interference filter (112) of this pixel (Pix)
Implementation Method 3
each pixel (Pix) comprises a stack (110A) of layers and, in this stack (110A), an interference filter (112) is defined
Implementation Method 4
the layers (110A) through which this waveguide (114) passes are dielectric layers and each waveguide (114) is made of one or more materials, each having a refractive index whose real part is greater than the real part of the refractive index of each of the dielectric layers (110A) through which this waveguide (114) passes
Data Source
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AI summary
This description relates to a pixelated filter in which each pixel (Pix) of the pixelated filter (108) comprises an interference filter (112) having a stack of layers (11A), and one or more waveguides (114) each passing through all or part of the layers (110A) of said interference filter (112). In each pixel (Pix) of the pixelated filter (108), the waveguide(s) are configured to guide at least one optical mode and such that an evanescent portion of said at least one guided mode is filtered by the interference filter (112) of said pixel (Pix).