Tunable Fabry-Perot Filter Element Using Silicon-on-Nothing Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for tunable optical filter elements that offer high resolution, a small footprint, and a large target spectrum while maintaining low complexity and cost-effectiveness, particularly for miniaturized spectrometers used in mobile devices and hyperspectral imaging applications.
Innovation Solution
A tunable Fabry-Perot filter element is designed with a first and second FP filter stack arranged on movable carrier elements, where the distance between them is adjustable using mechanical spring elements and an actuation structure, forming a silicon-on-nothing (SON) structure for enhanced stiffness and manufacturing simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional FP filter designs are used, then high resolution can be achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The filter is divided into multiple discrete FP filter stacks (first, second, third, fourth stacks) arranged in series, each contributing to the overall spectral filtering. This segmentation allows complex spectral resolution requirements to be achieved through simpler individual stacks rather than one complex monolithic filter.
Solution Approach 2:
Multiple FP filter stacks are combined in a single integrated device structure with shared components (substrate, electrodes, dielectric layers). The merging of these stacks achieves high spectral resolution through cumulative filtering effect while reducing overall device complexity compared to separate filter devices.
2Area of moving object
If miniaturized spectrometer designs are implemented, then small footprint is achieved, but manufacturing cost and complexity increase
Solution Approach 1:
The dielectric structure serves multiple functions simultaneously: it provides mechanical support for the FP filter stacks, acts as an insulator for the interdigitated electrodes, and forms the cavity structure for the resonant filtering. This multi-functionality reduces the number of separate components needed, simplifying manufacturing.
Solution Approach 2:
The interdigitated electrodes are nested within the dielectric structure, with fingers extending between dielectric layers. The FP filter stacks are nested within the same substrate area. This nesting arrangement achieves miniaturization by maximizing component density within a small footprint while maintaining manufacturability.
3Measurement precision
If high spectral resolution is pursued, then measurement precision improves, but device complexity increases
Solution Approach 1:
Each FP filter stack is designed with specific local characteristics (different numbers of dielectric layers, different electrode configurations) optimized for particular spectral regions. The first and second stacks handle different spectral ranges than the third and fourth stacks, allowing high overall resolution through specialized local designs rather than one uniformly complex structure.
Solution Approach 2:
The filter device employs tunable FP stacks where electrode voltages can be adjusted to dynamically change the resonant frequencies and filtering characteristics. This dynamic control allows the same physical structure to achieve high spectral resolution across multiple wavelength regions by electronically tuning rather than requiring fixed complex physical configurations.
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 configuration allows for precise tuning of the optical characteristics and transmission spectrum, enabling high-resolution spectrometry with a compact design that is cost-effective and suitable for various applications, including color recognition and gas analysis.
Implementation Method 1
a first Fabry-Perot (FP) filter stack (110) arranged at a movable first carrier element (120), a second FP filter stack (115) arranged in an opposing configuration to the first FP filter stack (110)
Implementation Method 2
The movable first carrier element (120) is formed as an SON structure (SON = silicon-on-nothing) in an SON substrate (130), wherein the SON structure is movable suspended by means of mechanical spring elements (135) to the SON substrate (130)
Data Source
Figure 1
Figure 2a~2b
Figure 2c
AI summary
According to an embodiment, a tunable Fabry-Perot (FP) filter element 100 comprises a first FP filter stack 110 arranged at a movable first carrier element 120, and a second FP filter stack 115 arranged in an opposing configuration to the first FP filter stack 110 at a second carrier element 125, wherein, upon an actuation, the first carrier element 120 with the first FP filter stack 110 is vertically movable with respect to the second carrier element 125 with the second FP filter stack 115, for adjusting the distance d1 between the first and second opposing FP filter stack 110, 115, and wherein the movable first carrier element 120 is formed as an SON structure (SON = silicon-on-nothing) in an SON substrate 130, wherein the SON structure 120 is movable suspended by means of a mechanical spring element 135 to the SON substrate 130.