Silicon Sub-Meta Lens Array for Thinner Pixel Sensors
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Solution Overview
Problem
Microlenses used in pixel sensors are thick and not suitable for miniaturized image sensors, such as near-infrared (NIR) image sensors, which limits their miniaturization and performance.
Innovation Solution
The use of meta lenses with holes in the top surface of a silicon layer to form sub-meta lenses, creating multiple focal points rather than a single point, thereby reducing optical paths and angular response of photons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microlenses are used in pixel sensors, then light focusing capability is achieved, but the sensor thickness increases and miniaturization is limited
Solution Approach 1:
The patent divides a single microlens into multiple sub-meta lenses arranged in an array. Each sub-meta lens has a specific lateral displacement and focal length configuration that collectively achieves the light focusing function while reducing the overall optical path length and sensor thickness required
Solution Approach 2:
The patent transitions from conventional three-dimensional microlens structures to a two-dimensional meta-lens array configuration on the sensor surface. This dimensional change allows light focusing to be achieved through lateral positioning and phase modulation rather than through thick vertical optical paths
2Reliability
If conventional microlenses are used, then optical path length is long, but this increases angular response and reduces signal-to-noise ratio
Solution Approach 1:
By segmenting the single optical path into multiple shorter optical paths through the sub-meta lens array, the patent reduces the overall optical path length. This segmentation also narrows the angular response of each individual sub-lens while maintaining collective light gathering capability, thereby improving signal-to-noise ratio
Solution Approach 2:
Each sub-meta lens in the array is designed with specific local optical properties including controlled lateral displacement and focal length. This local quality control allows each sub-lens to contribute optimally to the overall focusing function while minimizing angular response and optical path length
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 improves light focus and increases the signal-to-noise ratio (SNR) of pixel sensors, while also allowing for greater miniaturization of image sensors by reducing their dimensions, particularly the height of the pixel sensor.
Implementation Method 1
The plurality of holes in the top surface of the silicon medium form a plurality of sub-meta lenses that result in multiple light focusing points (also referred to as 'focal points') rather than a single point
Data Source
AI summary
A plurality of holes in a top surface of a silicon medium form a plurality of sub-meta lenses to result in multiple focal points rather than a single point (resulting from using a single meta lens). As a result, optical paths for incoming light are reduced as compared with a single optical path associated with a single meta lens, which in turn reduces angular response of incident photons. Thus, a pixel sensor including the plurality of sub-meta lenses experiences improved light focus and greater signal-to-noise ratio. Additionally, dimensions of the pixel sensor are reduced (particularly a height of the pixel sensor), which allows for greater miniaturization of an image sensor that includes the pixel sensor.