Hydrogenated Silicon Optical Filter for Angle-Stable Narrow Passbands
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Solution Overview
Problem
Conventional optical filters for gesture-recognition systems have wide passbands that shift with incidence angle, leading to increased ambient light transmission, reduced signal-to-noise ratio, and high fabrication costs due to numerous layers and thickness.
Innovation Solution
Employ hydrogenated silicon layers with high refractive index and low extinction coefficient for the filter stack, reducing layer count and thickness while maintaining high transmittance and blocking levels, and minimizing center-wavelength shift with incidence angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical filters using titanium dioxide and silicon dioxide layers are used, then the filter can block certain wavelengths, but the manufacturing precision is poor due to sensitivity to layer thickness variations and the filters cannot be effectively cleaned when contaminated
Solution Approach 1:
The patent changes the material parameters from conventional titanium dioxide/silicon dioxide to hydrogenated silicon/fluorinated magnesium oxide, which fundamentally alters the optical properties and manufacturing characteristics. This material substitution enables both improved manufacturing precision through reduced sensitivity to thickness variations and the ability to clean contaminated filters by removing the top layer.
Solution Approach 2:
The patent uses composite material structures with alternating layers of hydrogenated silicon and fluorinated magnesium oxide. This composite approach creates a filter stack where each material contributes specific properties: hydrogenated silicon provides absorption characteristics while fluorinated magnesium oxide provides structural stability and cleanability, together achieving both manufacturing precision and ease of maintenance.
2Ease of operation
If the optical filter is cleaned by removing the top layer, then contamination is eliminated, but the filter structure is damaged or destroyed
Solution Approach 1:
The patent divides the optical filter into separable layers where the top hydrogenated silicon layer can be removed independently from the underlying substrate and support structures. This segmentation allows the contaminable top layer to be discarded and replaced without affecting the structural integrity of the remaining filter stack, enabling cleanability without destroying the overall filter structure.
Solution Approach 2:
The patent introduces a sacrificial top layer that acts as an intermediary between the external environment and the critical filter structure. This top layer absorbs contamination and can be removed, protecting the underlying functional layers from damage. The intermediary layer enables cleaning operations without transmitting mechanical stress or damage to the core filter structure.
3Ease of operation
If hydrogenated silicon layers are used, then the filter can be cleaned by removing the top layer, but the manufacturing precision requires atomic layer deposition technology
Solution Approach 1:
The patent changes the deposition parameters and material properties to enable atomic layer deposition of hydrogenated silicon. This parameter change in the manufacturing process, while increasing technological complexity, enables precise control of layer thickness at the atomic level, which is necessary for achieving the desired optical performance and enabling the cleanable structure. The advanced deposition technology compensates for the increased device complexity by providing superior manufacturing precision.
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 optical filter achieves narrow passbands with minimal wavelength shift, improved signal-to-noise ratio, and reduced fabrication complexity and cost.
Implementation Method 1
The optical filter comprises a filter stack on a first side of a substrate, the filter stack includes alternating layers of hydrogenated silicon and layers of a lower-refractive-index material
Implementation Method 2
the filter stack includes alternating layers of hydrogenated silicon and layers of a lower-refractive-index material
Data Source
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AI summary
An optical filter is provided. The optical filter comprises a filter stack on a first side of a substrate, the filter stack includes alternating layers of hydrogenated silicon and layers of a lower-refractive-index material. A system comprising the optical filter is also provided.