Dielectric Resonant Filter Array for Uniform Wavelength Detection
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Solution Overview
Problem
Existing hyperspectral cameras face challenges in achieving high spatial resolution while utilizing multiwavelength information due to nonuniformity in peak intervals and line widths of transmission spectra, and fabrication issues with organic materials and conventional Fabry-Perot filters.
Innovation Solution
A photodetection device with a filter array comprising alternating dielectric layers in reflective layers, each with varying refractive indices and thicknesses, to create resonant structures with distinct modes, improving wavelength resolution and uniformity across wavelength regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Fabry-Perot filters or organic materials are used, then multiwavelength information can be acquired, but nonuniformity in peak intervals and line widths occurs and fabrication issues arise
Solution Approach 1:
The patent uses a composite structure consisting of multiple dielectric layers with alternating high and low refractive indices. This composite material approach creates a resonant cavity filter that achieves uniform transmission spectra characteristics while avoiding the fabrication issues of organic materials and conventional Fabry-Perot filters. The specific composite structure includes layers such as TiO2 (high refractive index) and SiO2 (low refractive index) arranged in a periodic pattern.
Solution Approach 2:
The patent applies local quality by varying the thickness of individual dielectric layers within the composite structure. Each layer has a specific thickness designed to achieve the desired resonant frequencies and transmission characteristics at different wavelengths. This local variation in layer thickness enables precise control over the transmission spectrum while maintaining overall uniformity across the filter array.
2Measurement precision
If high spatial resolution is achieved, then detailed physical properties can be detected, but device complexity and fabrication difficulty increase
Solution Approach 1:
The patent segments the filter array into multiple independent filter units, each corresponding to a specific pixel or group of pixels on the image sensor. Each filter unit is a self-contained resonant cavity structure that can be designed and fabricated independently. This segmentation allows for high spatial resolution by assigning specific wavelength filtering functions to specific spatial locations while simplifying the overall fabrication process.
Solution Approach 2:
The patent creates a universal filter structure that can detect multiple wavelengths simultaneously through the resonant cavity design. The same basic filter structure can be tuned to different wavelength ranges by adjusting the dielectric layer thicknesses and refractive indices, allowing a single device design to serve multiple detection purposes across the visible and near-infrared spectrum.
3Ease of manufacture
If conventional filter structures are used, then device fabrication is simpler, but uniformity in transmission spectra across wavelength regions deteriorates
Solution Approach 1:
The patent achieves uniform transmission spectra by precisely controlling the parameters of the dielectric layers, specifically the thickness and refractive index of each layer. By adjusting these parameters during the design phase, the filter structure compensates for fabrication variations and achieves consistent transmission characteristics across different wavelength regions. The periodic structure with alternating high and low refractive index layers provides robustness against manufacturing tolerances.
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 device achieves improved wavelength resolution and uniformity in light detection, enabling multiwavelength imaging with reduced nonuniformity in peak intervals and line widths, facilitating high-resolution multiwavelength image acquisition.
Implementation Method 1
an intermediate layer between the first reflective layer and the second reflective layer and having a resonant structure having a plurality of resonant modes differing in order from each other
Implementation Method 2
The first reflective layer includes a plurality of first dielectric layers each having a first refractive index and a plurality of second dielectric layers each having a second refractive index that is higher than the first refractive index. The plurality of first dielectric layers and the plurality of second dielectric layers are alternately disposed in the first reflective layer.
Data Source
AI summary
A photodetection device includes: a filter array including a plurality of filters arranged in a two-dimensional array, the plurality of filters including a first filter and a second filter, the first filter and the second filter each including a first reflective layer, a second reflective layer, and an intermediate layer between the first reflective layer and the second reflective layer and having a resonant structure having a plurality of resonant modes differing in order from each other, at least one selected from the group consisting of a refractive index and a thickness of the intermediate layer of the first filter being different from the at least one selected from the group consisting of a refractive index and a thickness of the intermediate layer of the second filter; and an image sensor disposed at a position where the image senor receives light having passed through the filter array.