Metasurface Image Sensor for High-Transmittance Spectral Splitting
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Solution Overview
Problem
Current image sensors using Bayer color filters have low light utilization, resulting in reduced imaging quality and color fidelity due to excessive light filtering, which limits the ability to capture a continuous visible light spectrum effectively.
Innovation Solution
A metasurface structure with a rotationally symmetric design and spatial transmission phase gradient is used to transmit optical signals at different frequency bands directly to corresponding optical-to-electrical conversion elements, replacing traditional light filtering with a light splitting manner, thereby improving light transmittance and reducing polarization dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a Bayer color filter is used to obtain color information, then color picture capability is improved, but light utilization deteriorates (more than 70% of light is filtered out)
Solution Approach 1:
The patent segments the optical signal by frequency band using a metasurface structure with different microstructures (first, second, and third microstructures) that direct different frequency bands to different optical-to-electrical conversion elements. This segmentation replaces the Bayer filter's wavelength-selective absorption with a spatial separation approach, allowing all light to reach conversion elements while maintaining color information capability.
Solution Approach 2:
The metasurface structure acts as an intermediary between the incoming optical signal and the optical-to-electrical conversion elements. It spatially modulates the optical signal by directing different frequency bands to different conversion elements through its microstructure arrangement, thereby preserving both color information and light energy without the need for traditional color filters.
2Measurement precision
If traditional light filtering is used to separate color channels, then color discrimination is improved, but light transmittance deteriorates
Solution Approach 1:
The patent transitions from spectral dimension filtering (Bayer filter that blocks most wavelengths) to spatial dimension separation (metasurface that directs all wavelengths to different spatial locations). By changing the dimension of separation from wavelength-based filtering to position-based routing, all light is transmitted while color discrimination is maintained through spatial assignment of frequency bands to different conversion elements.
3Loss of information
If a color filtering system is introduced to achieve color imaging, then color fidelity is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of color filtering and light guiding into a single metasurface structure. The metasurface integrates the frequency-selective routing function directly at the optical interface, eliminating the need for separate color filter layers and complex filtering systems. This consolidation maintains color fidelity while reducing overall system complexity.
4Measurement precision
If conventional optical filtering is used to capture spectral information, then spectral channel separation is improved, but polarization dependence increases
Solution Approach 1:
The patent employs asymmetric microstructure designs within the metasurface (different first, second, and third microstructures for different frequency bands) that achieve spectral separation without relying on polarization-sensitive filtering. The asymmetric geometries are configured to provide frequency-selective phase modulation and directional control that is independent of incident light polarization, thereby eliminating polarization dependence while maintaining spectral channel separation.
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 enhances light utilization and imaging quality by allowing more frequency spectrum information to be captured with minimal light loss, improving color fidelity and reducing spectral information loss.
Implementation Method 1
A metasurface structure with a rotationally symmetric design and spatial transmission phase gradient is used to transmit optical signals at different frequency bands directly to corresponding optical-to-electrical conversion elements
Implementation Method 2
The image sensor is configured to convert an optical signal of an image into an analog electrical signal
Data Source
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Figure 4~6(c)
Figure 7(a)~7(c)
AI summary
This application provides an image sensor and a preparation method thereof, and an electronic device. The image sensor includes an array of metasurface structures and an array of optical-to-electrical conversion units. The array of metasurface structures is located above the array of optical-to-electrical conversion units, the optical-to-electrical conversion unit includes a plurality of optical-to-electrical conversion elements, each optical-to-electrical conversion element in the optical-to-electrical conversion unit corresponds to one frequency band in a spectrum, the metasurface structure includes a first substrate and a microstructure located above the first substrate, and the first substrate is configured to transmit an optical-to-electrical conversion element corresponding to each frequency band, the microstructure is a rotationally symmetric structure, and a rotation angle of the rotationally symmetric structure is less than or equal to 90 degrees. The technical solutions of this application can improve light transmittance of each spectral channel, and improves overall light utilization of the image sensor.