Flat-Surface Metastructure for Low-Scattering Light Transmission
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Solution Overview
Problem
Existing metasurface structural bodies face challenges in achieving desired optical characteristics due to scattered transmitted light and restricted material selection on the front surface, primarily because the material used on the substrate forms irregularities on the fine structures, leading to irregular light transmission directions.
Innovation Solution
A metasurface structural body with a flat surface composed of antenna end surfaces and adjacent-portion end surfaces, where the antennas have a different refractive index than the base member, allowing for a high degree of freedom in material selection and reducing light scattering, along with a manufacturing method involving layer formation, etching, deposition, and removal steps to create a flat surface without chemical mechanical polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If material of the same type as substrate is provided to bury spaces between fine structures, then structural integrity is improved, but light scattering increases and optical characteristics deteriorate
Solution Approach 1:
The patent extracts the problematic material filling step that causes light scattering. Instead of filling spaces between antennas with substrate material, the invention leaves them as air gaps or fills with low-refractive-index materials, thereby removing the source of irregular light transmission while maintaining structural integrity through alternative means.
Solution Approach 2:
The patent applies different material properties to different regions: the front surface region uses materials optimized for optical transparency and flatness (such as transparent resists or low-refractive-index materials), while the base substrate maintains its structural material properties. This local differentiation allows simultaneous achievement of structural integrity and optical performance.
2Ease of manufacture
If material of the same type as substrate is provided on fine structures, then material selection is restricted, but manufacturing process is simplified
Solution Approach 1:
The manufacturing process is segmented into distinct stages: first forming the antenna structures, then applying a separate front surface material layer. This segmentation allows independent optimization of each layer's material properties - the antenna material for optical functionality and the front surface material for optical transparency and flatness, thereby achieving both manufacturing feasibility and material versatility.
Solution Approach 2:
The patent introduces an intermediary material layer (such as a transparent resist or buffer layer) between the substrate and the final front surface. This intermediary layer acts as a mediator that simplifies the manufacturing process by providing a uniform deposition surface while simultaneously enabling greater material selection freedom for the final optical surface.
3Manufacturing precision
If chemical mechanical polishing is used to create flat surface, then surface flatness is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent performs preliminary action by designing the antenna structures and spacing such that the front surface naturally forms a sufficiently flat surface after deposition, eliminating or reducing the need for subsequent chemical mechanical polishing. The structures are configured to achieve optical-grade flatness as an inherent property rather than requiring post-processing.
Solution Approach 2:
The patent replaces the mechanical/chemical process of chemical mechanical polishing with a deposition-based approach. By carefully controlling the deposition process and antenna structure geometry, the desired surface flatness is achieved through material deposition and structural design rather than mechanical removal, thereby simplifying the manufacturing process.
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 enables the achievement of desired optical characteristics by suppressing irregular light transmission and allowing for the selection of materials that improve transmittance and reduce interfacial reflection, resulting in enhanced optical functionality.
Implementation Method 1
The adjacent portion has a second refractive index different from the first refractive index, and constitutes a remaining part of the first surface. In the metasurface structural body, the plurality of antenna end surfaces and the adjacent-portion end surface constitute a flat surface as the first surface.
Implementation Method 2
since the material of the same type as the substrate has a front surface on which irregularities corresponding to the arrangement of the fine structures are formed, transmitted light is scattered. Accordingly, the transmitted light travels in irregular directions
Data Source
AI summary
The present disclosure relates to a metasurface structural body or the like having a structure for achieving desired optical characteristics. The metasurface structural body includes a base member having a first surface and a second surface opposing each other, and a plurality of antennas as a plurality of fine structures arranged along the first surface. The base member has a base portion and an adjacent portion. The antennas each has a first refractive index and an antenna end surface constituting a part of the first surface. The adjacent portion is provided such that a part thereof is positioned between the antennas, the adjacent portion having a second refractive index different from the first refractive index and an adjacent-portion end surface constituting a remaining part of the first surface. The antenna end surfaces and the adjacent-portion end surface form a flat surface as the first surface.