Image Sensor Metasurface Structure for Light Field Direction Capture
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Solution Overview
Problem
Conventional image sensors can only record light intensity and lack the capability to capture direction information of incident radiation, leading to unsatisfactory resolution and signal strength in light field imaging, as seen in plenoptic cameras with low resolution due to microlens and micro pixel array limitations, and other approaches that block light with offset apertures.
Innovation Solution
An image sensor with a metasurface structure is introduced, positioned at the back side of the semiconductor substrate, featuring a periodic pattern of alternating protrusions and trenches that interact with incident radiation, enhancing local optical fields and quantum efficiency while allowing for light-matter interaction, and potentially serving as a color filter layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional image sensors are used to record light intensity, then the imaging function is achieved, but the direction information of incident radiation cannot be captured
Solution Approach 1:
The patent introduces a metasurface structure with sub-wavelength protrusions and trenches that adds spatial dimensionality to light detection. By creating periodic variations in the surface topology at the nanoscale, the sensor can encode directional information into the optical field distribution, allowing conventional photodetectors to capture angular information without requiring complex multi-pixel arrays or microlens configurations.
Solution Approach 2:
The metasurface structure modifies optical parameters (light field intensity distribution, phase, and polarization) by introducing periodic geometric features with dimensions smaller than the wavelength of incident light. These parameter changes enable the extraction of directional information from the modified optical fields using standard detection methods, avoiding the need for complex sensor architectures.
2Loss of information
If plenoptic cameras with microlens and micro pixel array are used, then direction information can be captured, but the resolution is low
Solution Approach 1:
Instead of using spatial separation of microlenses and pixels in the plenoptic camera, this patent encodes directional information in the optical field parameters (intensity distribution, phase) through metasurface modulation. This allows conventional high-resolution pixel arrays to capture both spatial and angular information simultaneously, maintaining resolution while enabling light field imaging.
Solution Approach 2:
The patent replaces the mechanical/optical system of microlens arrays with a metasurface structure that uses sub-wavelength geometric features to modulate light. This substitution eliminates the resolution-limiting constraints of microlens pitch and pixel size, allowing the full resolution of the pixel array to be utilized for both spatial and angular information capture.
3Loss of information
If offset apertures are used to capture direction information, then angular data can be obtained, but light is blocked and signal strength is reduced
Solution Approach 1:
The metasurface structure functions as a porous-like nanoscale patterned layer that allows light to pass through while modulating its properties. The sub-wavelength protrusions and trenches create optical path differences and field intensity variations without physically blocking the light, thereby maintaining signal strength while encoding directional information in the transmitted optical field.
Solution Approach 2:
Rather than blocking light with offset apertures, the metasurface structure changes the parameters of the transmitted light (intensity distribution, phase, polarization) based on the incident angle. This parameter modulation approach preserves the majority of the incident light energy while still providing directional information through the modified optical field characteristics.
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 metasurface structure effectively enhances light field intensity distribution and quantum efficiency, enabling improved resolution and signal strength in capturing light field information, including direction, without blocking incident radiation.
Implementation Method 1
The metasurface structure includes a periodic pattern of alternating protrusions and trenches that interact with incident radiation, enhancing local optical fields and quantum efficiency while allowing for light-matter interaction
Implementation Method 2
The pixel sensors measure incident radiation (e.g., light)
Data Source
AI summary
Present disclosure provides a pixel for receiving an incident light, the pixel including a semiconductor substrate, a photo diode in the semiconductor substrate, and a metasurface structure over the semiconductor substrate. The metasurface structure has a first side and a second side opposite to the first side, the first side of the metasurface structure facing the semiconductor substrate, the second side of the metasurface structure facing the incident light. The metasurface structure includes a plurality of trenches at the second side, wherein the plurality of trenches have a same profile from a cross-sectional view.