Optical Filter Array Structure for Miniaturized Spectral Sensing
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Solution Overview
Problem
Existing optical filters, such as linear variable filters (LVFs), face challenges in process reproducibility, difficulty in miniaturization, and integration with photodetectors due to their linear structure, leading to reduced performance and compatibility issues with two-dimensional imaging sensors.
Innovation Solution
An optical filter design featuring first and second reflection layers with a dielectric region and buffer layer, allowing for alternately disposed materials with different refractive indices and volume ratios, enhancing process reproducibility and enabling monolithic integration with photodetectors while minimizing stray light effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear variable filter (LVF) with linear structure is used, then the transmission spectrum can be formed, but process reproducibility is poor and productivity is reduced
Solution Approach 1:
The patent divides the dielectric layer into multiple discrete dielectric patterns arranged in a two-dimensional array, where each pattern corresponds to a specific wavelength channel. This segmentation transforms the continuous linear structure into discrete modular units, enabling parallel processing and improving both process reproducibility and productivity through standardization.
Solution Approach 2:
The patent transitions from a one-dimensional linear structure to a two-dimensional array structure. The dielectric patterns are arranged in rows and columns, with each position in the array corresponding to a specific wavelength. This dimensional change enables compatibility with two-dimensional imaging sensors and significantly improves manufacturing efficiency through batch processing.
2Volume of moving object
If a linear variable filter (LVF) is used, then the transmission spectrum can be formed, but miniaturization is difficult due to height-to-length ratio constraints
Solution Approach 1:
The patent reconfigures the filter structure from a long linear arrangement to a compact two-dimensional array. By distributing wavelength channels across a 2D plane rather than along a single line, the overall length and height dimensions are reduced, enabling miniaturization of the spectrometer element while maintaining the required spectral resolution.
Solution Approach 2:
The patent changes the geometric parameters of the dielectric structures, using sub-wavelength sized dielectric patterns with specific width and spacing. By controlling the dimensions of individual dielectric elements to be smaller than the wavelength of light, the patent achieves compact sizing while maintaining optical performance through effective medium theory.
3Reliability
If the LVF is spaced apart from the photodetector array, then the linear structure can be maintained, but stray light effect increases and filter performance is lowered
Solution Approach 1:
The patent merges the filter structure directly with the photodetector array by placing dielectric patterns in direct contact with or immediate proximity to each photodetector element. This integration eliminates the need for spacing, removes stray light paths, and enables monolithic fabrication where the filter and detector are formed as a single integrated structure.
4Ease of manufacture
If substrates are attached to each other in planar optical filter, then the structure can be formed, but manufacturing process becomes difficult and costly
Solution Approach 1:
The patent combines multiple filter structures onto a single substrate by arranging dielectric patterns in a two-dimensional array on one continuous substrate. This eliminates the need to attach multiple separate substrates together, simplifying the manufacturing process to a single substrate fabrication step while reducing alignment complexity and production costs.
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 design achieves a miniaturized structure with improved productivity, enhanced performance, and reduced stray light effects, allowing for better integration with photodetectors and expanded wavelength variable range.
Implementation Method 1
a dielectric region interposed between the first and second reflection layers and in which two materials of which refractive indexes are different are alternately disposed
Implementation Method 2
The linear variable filter (LVF) kind of optical filter having a Fabry-Perot resonator structure
Implementation Method 3
a buffer layer disposed between the dielectric region and at least one of the first and second reflection layers
Data Source
AI summary
Provided is an optical filter including first and second reflection layers separated from each other, a dielectric region interposed between the first and second reflection layers and in which two materials of which refractive indexes are different are alternately disposed, and a buffer layer disposed between the dielectric region and at least one of the first and second reflection layers, wherein there are at least two filter regions in which relative volume ratios of the two materials alternately disposed are different.