Inverse Wire-Grid Polarizer High Contrast UV
Solution Overview
Problem
Manufacturing wire-grid polarizers with high contrast is challenging, especially for smaller wavelengths, as reducing the pitch of the wires is difficult and not always feasible.
Innovation Solution
The use of embedded, inverse wire-grid polarizers with ribs over a transparent substrate, gaps between the ribs, and a fill-layer that substantially fills the gaps and has an index of refraction greater than 1.7, optimizing the structure to achieve E∥ transmission greater than E⊥ transmission across various wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch of the wires/ribs is reduced to achieve high contrast, then the contrast improves, but the manufacturing difficulty increases significantly
Solution Approach 1:
The patent inverts the conventional wire-grid polarizer design by placing a high-index fill layer (n>1.7) within the gaps between ribs rather than in the ribs themselves. This inversion allows the structure to achieve high contrast through the fill layer's optical properties rather than through small pitch dimensions, thereby improving manufacturability while maintaining performance.
Solution Approach 2:
The patent changes the refractive index parameter of the fill layer to be greater than 1.7, which fundamentally alters the optical behavior of the polarizer. This parameter change enables high contrast performance without requiring reduced pitch, as the high-index fill layer provides the necessary optical contrast mechanism.
2Reliability
If the pitch of the wires/ribs is reduced to achieve high contrast for smaller wavelengths, then the contrast improves, but the manufacturing challenge becomes even more difficult
Solution Approach 1:
By inverting the design to place high-index material in the gaps rather than the ribs, the patent enables smaller wavelength polarization without requiring proportionally smaller pitch. The high-index fill layer provides the optical contrast mechanism, allowing the same pitch to work for smaller wavelengths where conventional designs would fail.
Solution Approach 2:
The patent uses a composite structure combining low-index ribs (or substrate) with high-index fill layer (n>1.7). This composite approach leverages the contrasting optical properties of the two materials to achieve high contrast for smaller wavelengths without the manufacturing challenges associated with uniformly small features.
3Ease of manufacture
If conventional wire-grid polarizer structures are used, then manufacturing is simpler, but contrast and performance are insufficient
Solution Approach 1:
The patent changes the refractive index parameter of the fill layer to exceed 1.7, which provides sufficient optical contrast for high-performance polarization. This parameter change enables both good manufacturability (using standard fabrication processes) and high contrast performance, resolving the trade-off between simplicity and performance.
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 improves the performance of wire-grid polarizers by enhancing contrast and manufacturability, allowing for high E∥ transmission and high contrast even in difficult-to-polarize regions of the electromagnetic spectrum, such as the ultraviolet range.
Implementation Method 1
the fill-layer can be transparent and can have an index of refraction greater than 1.7
Implementation Method 2
the ribs can be reflective
Data Source
AI summary
An embedded wire-grid polarizer (WGP) can include ribs 13 located over a surface of a transparent substrate 11, gaps 16 between the ribs 13, and a fill-layer 15 substantially filling the gaps 16. The fill-layer can have a relatively high index of refraction, such as greater than 1.4. At a wavelength of light incident upon the WGP, E∥ transmission can be greater than E⊥ transmission. E∥ is a polarization of light with an electric field oscillation parallel to a length L of the ribs, and E⊥ is a polarization of light with an electric field oscillation perpendicular to a length L of the ribs. This embedded, inverse WGP is especially useful for polarizing, with high WGP performance, small wavelength (high-energy) regions of the electromagnetic spectrum (e.g. UV) which are difficult to polarize with conventional WGPs (E⊥ transmission >E∥ transmission).