Waveguide Aperture Filter for Image Sensor Color Separation
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Solution Overview
Problem
Existing image sensors require additional infrared filters, lose significant light intensity through color filters, have limited color separation, and are angle-dependent in light collection, leading to inefficiencies and chromatic aberrations in passive optical components.
Innovation Solution
An image sensor with a first layer containing apertures that act as a waveguide filter, attenuating infrared light and allowing visible light to propagate based on its frequency, eliminating the need for conventional color filters and enhancing color separation and angle-independent light collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color filter arrays are used for color separation, then color filtering is achieved, but 50% or more of light intensity is lost
Solution Approach 1:
The patent replaces conventional absorptive color filters with a waveguide-based optical system. The waveguide structure uses total internal reflection and mode propagation physics to guide different wavelengths to different pixels, eliminating the need for absorptive filtering materials and reducing light loss significantly.
Solution Approach 2:
The invention changes the filtering mechanism from absorptive (conventional filters) to waveguide-mode-based separation. By adjusting waveguide dimensions, refractive indices, and geometric configurations, the system achieves wavelength-dependent light routing without absorbing unwanted wavelengths, thereby preserving light intensity.
2Measurement precision
If conventional color filter arrays are used, then color filtering is provided, but the structure becomes complex and fabrication is difficult
Solution Approach 1:
The patent merges the color separation function with the existing pixel array structure by integrating waveguide layers directly above the sensor pixels. This eliminates the need for separate color filter arrays and complex alignment processes, simplifying both structure and fabrication.
Solution Approach 2:
The waveguide-based system replaces mechanically complex color filter arrays with a planar optical structure that can be fabricated using standard semiconductor processing techniques, such as depositing dielectric layers and patterning waveguide regions, thereby simplifying manufacturing.
3Measurement precision
If standard image sensors are used, then light detection is achieved, but angle-dependent light collection efficiency occurs
Solution Approach 1:
The waveguide layer acts as an intermediary between incident light and the pixel sensors. It captures light over a wide angular range and guides it to the pixels through total internal reflection, decoupling the collection efficiency from the incident angle and enabling angle-independent detection.
4Object-affected harmful factors
If additional infrared filters are added to image sensors, then infrared contamination is reduced, but device complexity increases
Solution Approach 1:
The waveguide structure serves multiple functions simultaneously: it performs color separation for visible light and acts as an infrared filter by guiding only specific wavelength ranges to the pixels. This multi-functionality eliminates the need for separate infrared filtering layers, reducing overall 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 provides efficient color separation, reduces light spillover, and improves imaging performance by using standard chip fabrication to create a structurally simple image sensor with improved light collection efficiency and reduced angle dependence.
Implementation Method 1
The cross sectional size of the at least one aperture is configured to provide a cutoff frequency so that incident radiation with a frequency below the cutoff frequency is attenuated inside the at least one aperture and incident radiation with a frequency above the cutoff frequency propagates through the at least one aperture
Data Source
AI summary
In some disclosed embodiments, an image sensor is provided for recording incident radiation may include a first layer for filtering the incident radiation by attenuating incident radiation with a frequency below a cutoff frequency and a second light-sensitive layer for absorbing radiation passing through the first layer. The first layer may precede the second light-sensitive layer in a direction of propagation of the incident radiation and the first layer includes at least one aperture passing through the first layer to the second light-sensitive layer for propagating radiation therethrough. The cross sectional size of the at least one aperture may be configured to provide a cutoff frequency so that incident radiation with a frequency below the cutoff frequency is attenuated inside the at least one aperture and incident radiation with a frequency above the cutoff frequency propagates through the at least one aperture.