Transmissive Meta-Surface Polarization Separation at Normal Incidence
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Solution Overview
Problem
Existing polarization converting assemblies (PCAs) are bulky, complex, and costly due to their large size and weight, requiring significant axial space and complex manufacturing processes, and they do not efficiently separate polarization states at normal angles of incidence without increasing the angular spread of the output light.
Innovation Solution
Employing transmissive meta-surfaces, including meta-surface phase retarders and deflectors, fabricated using high-throughput techniques, to separate and transform polarization states at normal angles of incidence, reducing axial thickness and weight, and integrating with pixelated displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional reflective polarization beam splitters are used, then polarization separation is achieved, but the assembly becomes bulky and occupies significant axial space
Solution Approach 1:
The patent replaces traditional reflective polarization beam splitters with transmissive meta-optical structures that use geometric phase (Pancharatnam-Berry phase) to achieve polarization separation. This substitution eliminates the need for bulky reflective optics and multiple optical components, reducing axial space from centimeters to millimeters while maintaining polarization separation functionality.
Solution Approach 2:
The patent changes the operational parameters by using geometric phase modulation instead of dynamic phase modulation. This allows the polarization beam splitter to operate at normal incidence angles rather than requiring 45-degree angles, and enables the use of transmissive meta-surfaces instead of reflective coatings, significantly reducing the axial thickness of the assembly.
2Length of stationary object
If prism arrays are used to reduce axial thickness, then the axial space is reduced, but manufacturing becomes labor-intensive and expensive
Solution Approach 1:
The patent divides the meta-optical structure into discrete meta-atoms (nano-scale resonators) arranged in periodic arrays on planar substrates. Each meta-atom can be independently designed and fabricated using standard lithography techniques, enabling high-volume manufacturing through wafer-level processing rather than labor-intensive prism assembly.
Solution Approach 2:
The patent replaces mechanical prism assemblies with planar meta-optical structures that can be fabricated using semiconductor manufacturing techniques. This substitution enables automated, high-throughput production through lithography, deposition, and etching processes, eliminating the need for manual alignment and assembly of optical prisms.
3Length of stationary object
If transmissive meta-surface polarization beam splitters are used, then axial thickness is reduced, but the angular spread of output light increases
Solution Approach 1:
The patent optimizes the geometric parameters of meta-atoms (size, shape, orientation, and material properties) to control the phase gradient and diffraction angles. By carefully tuning these parameters, the design achieves polarization separation at normal incidence while minimizing angular spread of the output beams, balancing compactness with beam quality.
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 compact, efficient polarization conversion with reduced angular spread, enabling integration with pixelated displays and fabrication in high volumes using established techniques.
Implementation Method 1
the meta-surface is designed to exhibit optical anisotropy when light is incident onto the meta-surface at a normal angle
Implementation Method 2
The geometric phase polarization diffraction gratings diffract incident light into (0,±1) diffraction orders as left-hand circularly polarized (LCP) and right-hand circularly polarized (RCP) light
Implementation Method 3
geometric phase diffraction gratings, also known as Pancharatnam-Berry phase (PBP) gratings. The geometric phase polarization diffraction gratings diffract incident light into (0,±1) diffraction orders
Data Source
AI summary
A polarization-separating device includes an optically transmitting substrate and a transmissive meta-surface structure disposed on the substrate. The transmissive meta-surface structure is configured to receive incident light and angularly separate the incident light into orthogonal polarization components. A first polarization component is transmitted by the meta-surface structure without altering a propagation direction of the first polarization component. A a second polarization component is directed by the meta-surface structure at a non-zero angle with respect to a propagation direction of the incident light.