Metal Nanostructure Optical Filter for High Resolution
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Solution Overview
Problem
Existing optical filters, such as linear variable filters, face challenges in process reproducibility, resolution, and compatibility with two-dimensional imaging sensors due to their linear structure, which limits their ability to produce filters with various wavelength bands and high resolving power.
Innovation Solution
The use of metal nanostructures with different refractive indices in multiple layers allows for the creation of optical filters with varying resonance wavelengths, enabling the manufacture of filters with multiple wavelength bands and high resolving power by adjusting the refractive index and material properties of the nanostructures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear variable filter with varying cavity thickness is used, then the filter can achieve wavelength selection, but the process reproducibility deteriorates and manufacturing complexity increases
Solution Approach 1:
The continuous linear variable filter structure is segmented into discrete metal nanostructure units arranged in arrays. Each nanostructure acts as an independent resonant element, converting the continuous thickness variation problem into discrete, manufacturable units that can be precisely controlled through standard fabrication processes.
Solution Approach 2:
The invention changes the controlling parameter from continuous cavity thickness to discrete metal nanostructure dimensions (size, shape, material composition). This parameter transformation enables precise wavelength control through nanostructure geometry while maintaining compatibility with standard semiconductor manufacturing processes, thereby improving process reproducibility.
2Measurement precision
If a linear variable filter is used, then wavelength filtering is achieved, but the spectrometer element size cannot be minimized
Solution Approach 1:
The invention transitions from a one-dimensional linear variable filter (varying thickness along one axis) to a two-dimensional array of metal nanostructures. This dimensional change allows wavelength encoding across the spatial plane rather than requiring long linear paths, enabling miniaturization of the spectrometer element while maintaining resolution through the compact 2D nanostructure arrangement.
3Measurement precision
If a linear variable filter is used, then wavelength selection is possible, but compatibility with two-dimensional imaging sensor technology deteriorates
Solution Approach 1:
The metal nanostructure array serves multiple functions simultaneously: it acts as the wavelength-selective filter, the structural framework for 2D arrangement, and the interface layer for integration with photodetector arrays. This multi-functionality enables direct monolithic integration with 2D imaging sensors, eliminating the need for separate filter and sensor assemblies and improving process compatibility.
4Ease of manufacture
If the LVF is spaced apart from the photodetector array, then assembly is simplified, but filter performance deteriorates due to stray light effect
Solution Approach 1:
The invention merges the filter structure and photodetector array into a single monolithic integrated device. The metal nanostructures are fabricated directly on the substrate in close proximity to or in direct contact with the photodetectors, eliminating air gaps and mechanical assembly steps. This integration prevents stray light paths while maintaining manufacturing feasibility through standard semiconductor fabrication processes.
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 simplifies the production of optical filters with various wavelength bands and high resolving power, reducing the need for complex processes and multiple nanostructures, leading to miniaturization and reduced sensitivity to external environments.
Implementation Method 1
a central wavelength of a transmission or cut-off spectrum by plasmonic resonance of a metal nanostructure
Data Source
AI summary
Provided is an optical filter including a first filter region including a first layer of a first refractive index and a plurality of first metal nanostructures in the first layer, and a second filter region including a second layer of a second refractive index and a plurality of second metal nanostructures in the second layer, wherein the first refractive index is different from the second refractive index.