Chip-Scale Spectrometer Plasmonic Filter Microlens Integration
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Solution Overview
Problem
Existing spectrometers for mobile devices are complex, costly, and prone to manufacturing variations, limiting their deployment in consumer handheld devices due to angle-dependent plasmonic filter arrays and the need for external optics.
Innovation Solution
A spectrometer design incorporating a plasmonic filter/microlens arrangement with a composite filter-microlens structure in a single metallic layer, featuring a diffractive lens and plasmonic microlens array that focuses and spectrally filters light, allowing for a large field of view and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If plasmonic filter arrays are used in spectrometers, then spectral filtering capability is improved, but angle dependence causes transmission variation and limits field of view
Solution Approach 1:
The patent combines the plasmonic filter array with a microlens array into an integrated structure where each microlens is positioned directly over corresponding filter elements. This merging allows the microlenses to focus incident light onto the filters at various angles, enabling the system to maintain spectral filtering performance while accepting light from a wider field of view without requiring external optics.
Solution Approach 2:
The microlens array acts as an intermediary between the incoming light and the plasmonic filter array. The microlenses pre-condition the light by focusing it onto the filter elements, thereby mediating the angle-dependent transmission issue and enabling the filters to effectively process light from a broader angular range.
2Measurement precision
If external optics are added to limit field of view, then spectral measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the field of view control function directly into the sensor chip by integrating microlenses and filters at the wafer level. This eliminates the need for separate external optics and complex assembly steps, achieving both field of view limitation and spectral measurement accuracy while simplifying the overall device structure.
Solution Approach 2:
The integrated microlens-filter array on the sensor chip performs field of view control autonomously without requiring external optical components. The structure is self-sufficient, with the microlenses and filters working together to define the effective field of view as part of the intrinsic sensor architecture.
3Measurement precision
If plasmonic filters are used, then spectral selectivity is improved, but manufacturing process variation causes transmission function variation
Solution Approach 1:
The patent implements a feedback mechanism where the actual transmission characteristics of each pixel's plasmonic filter are measured during or after fabrication. These measured characteristics are then used to generate pixel-specific calibration data that compensates for manufacturing variations, ensuring consistent spectral selectivity across all pixels despite process variations.
Solution Approach 2:
The patent compensates for manufacturing variations by changing the operational parameters of each pixel based on its actual characteristics. By adjusting the spectral response interpretation for each pixel according to its measured transmission function, the system maintains uniform spectral selectivity across all pixels despite variations in physical dimensions or material properties.
4Ease of manufacture
If wafer-level integration is implemented, then manufacturing cost and complexity are reduced, but maintaining spectral accuracy across process variation becomes more difficult
Solution Approach 1:
The patent uses feedback from measured pixel characteristics to generate calibration data that compensates for wafer-level process variations. This allows the system to maintain spectral accuracy across all pixels even though they are fabricated using standard wafer-level processes with inherent variations, thereby enabling cost-effective mass production without sacrificing measurement quality.
Solution Approach 2:
The patent compensates for process variations by dynamically adjusting the spectral interpretation parameters for each pixel based on its actual transmission characteristics. This parameter adjustment approach allows wafer-level integration to produce consistent spectral measurements across all pixels despite manufacturing variations in filter dimensions or material 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
The solution provides a compact, cost-effective, and robust spectrometer with improved spectral accuracy and stability across process variations, enabling mass production and integration in mobile devices without the need for external optics.
Implementation Method 1
a microlens array and a filter array are consolidated into a single composite filter-microlens array
Implementation Method 2
spectral scans can be used to monitor atmospheric conditions such as the constituents of the gas
Data Source
AI summary
A spectrometer having a plasmonic filter/microlens arrangement is provided. The spectrometer can include a controller; an image sensor with a pixel array formed by a plurality of pixels coupled to the controller; and an optical layer over the image sensor. The optical layer can include a plasmonic microlens array having a plurality of microlenses positioned over the spacer layer, each microlens of the plasmonic microlens array focusing light on one of the plurality of pixels, and a plasmonic filter array arranged with the plasmonic microlens array such that light incident on each of the plurality of pixels has a transmission function. The microlenses and plasmonic filters can be formed of a composite structure.