Fabry-Pérot Light Sensor Spacer for Infrared Spectral Detection
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Solution Overview
Problem
Existing light sensors manufactured using thin-film technology face challenges in forming Fabry-Perot filters without damaging photo-sensitive elements, particularly when detecting spectral information extending into infrared wavelengths.
Innovation Solution
A light sensor design featuring a spacer element with two different materials, arranged between the upper and lower reflective elements, which forms a resonance structure allowing for controlled resonance wavelengths without requiring the filter to be above the photo-sensitive element, enabling flexible manufacturing and protection of the photo-sensitive element during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Fabry-Pérot filters are formed on photo-sensitive elements using thin-film technology, then spectral information detection capability is improved, but the photo-sensitive elements are damaged or harmed during manufacturing
Solution Approach 1:
The device is segmented into distinct functional layers: the photo-sensitive element layer and the Fabry-Pérot filter layer are separated in time of formation. The spacer element is introduced as an intermediate structure that enables this segmentation, allowing the photo-sensitive elements to be formed first and protected, then the filters to be formed later without damaging the sensitive elements.
Solution Approach 2:
The photo-sensitive elements are formed in advance before the Fabry-Pérot filters are created. This preliminary formation allows the sensitive elements to be established in a protected state, and subsequent filter formation processes can proceed without risking damage to the photo-sensitive materials.
2Adaptability or versatility
If Fabry-Pérot filters are formed above photo-sensitive elements, then wavelength band selection is achieved, but manufacturing complexity increases due to required patterning on photo-sensitive elements
Solution Approach 1:
The invention moves the wavelength selection functionality from the lateral dimension (patterning on the photo-sensitive element surface) to the vertical dimension (spacer element thickness and filter cavity depth). By controlling the spacer thickness and filter layer properties in the vertical direction, different wavelength bands are selected without requiring complex lateral patterning of the photo-sensitive elements themselves.
Solution Approach 2:
The wavelength selection is achieved by changing physical parameters of the spacer and filter layers, specifically the spacer element thickness and the optical cavity depth. By adjusting these dimensional parameters during deposition, different resonance wavelengths are achieved, providing wavelength band selection without increasing manufacturing process complexity.
3Adaptability or versatility
If thin-film technology is used for photo-sensitive elements, then detection into infrared wavelengths is enabled, but subsequent filter formation damages the photo-sensitive elements
Solution Approach 1:
The photo-sensitive elements are formed in advance using thin-film technology to enable infrared detection, then the spacer element is deposited to protect them. Subsequent filter formation occurs after the sensitive elements are already in place and protected, eliminating the harmful effects of filter formation on the thin-film photo-sensitive materials.
Solution Approach 2:
The spacer element acts as an intermediary structure between the photo-sensitive elements and the Fabry-Pérot filters. This intermediate layer protects the thin-film photo-sensitive elements from direct exposure to damaging manufacturing processes while still allowing optical functionality to be achieved through the spacer's optical properties.
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 design allows for the detection of multiple wavelength bands with improved spectral resolution, protecting the photo-sensitive elements from manufacturing damage and facilitating the use of thin-film technology, while also enabling spatial and spectral imaging capabilities.
Implementation Method 1
the stack of layers define a resonance structure between the upper reflective element and the lower reflective element for providing a resonance of light dependent on a wavelength of the light
Implementation Method 2
By changing an effective refractive index of a material between the two reflective surfaces, a resonant wavelength of the Fabry-Pérot filter is changed
Implementation Method 3
two reflective surfaces which are spaced apart such that constructive interference of light having traveled different number of times between the reflective surfaces may be formed
Data Source
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AI summary
A light sensor (100) for spectrally resolved light detection, said light sensor (100) comprises: an upper reflective element (104); a lower reflective element (106); a photo-sensitive element (114) therebetween; a spacer element (108), configured to form the lower reflective element (106) or configured to be arranged between the upper (104) and the lower reflective element (106); wherein the elements form a stack of layers which define a resonance structure (102a, 102b, 102c) between the upper (104) and the lower reflective element (106) for providing a resonance of light; wherein the spacer element (108) comprises at least two different materials (110, 112), a distribution of which is different between different pixels in an array of pixels such that a resonance wavelength is different for different pixels; and wherein for a plurality of pixels, geometrical structures smaller than the resonance wavelength are defined by the at least two different materials (110, 112).