Metasurface Optical Member With Continuous Liquid Crystal Phase Control
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Solution Overview
Problem
Existing optical members with metasurface structures and liquid crystal layers struggle to achieve high reflectivity of electromagnetic waves in desired directions due to discontinuous phase changes and low refractive index variations, leading to inefficient wave steering.
Innovation Solution
An optical member comprising a reflective layer, a liquid crystal layer with immobilized rod-like liquid crystal compounds, and a metasurface structure where the in-plane refractive index continuously changes to match the arrangement direction of microstructures, allowing for continuous refractive index variation and improved phase modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical reflective plate is used, then the structure is simple and easy to manufacture, but the emission angle equals the incidence angle (specular reflection only), making it difficult to deliver radio waves deep into the room
Solution Approach 1:
The reflective plate is segmented into multiple resonators with different geometries (e.g., circular, square, triangular) arranged in specific patterns. Each resonator type reflects radio waves in different directions, enabling the entire structure to deliver waves deep into the room while maintaining manufacturing simplicity through modular design
Solution Approach 2:
Different regions of the reflective plate contain resonators with locally optimized geometries and arrangements. By varying the resonator shapes and orientations in different areas, the structure achieves directional control of radio waves to deliver them deep into the room while keeping each local region manufacturable
2Adaptability or versatility
If dynamic elements like liquid crystal are used to bend electromagnetic waves, then wave steering capability is improved, but the device complexity increases due to multiple layers and control mechanisms
Solution Approach 1:
The liquid crystal layer and electrode structures are extracted and replaced with a static metasurface composed of resonators. This extraction eliminates the need for dynamic control mechanisms while preserving wave steering capability through the geometric design of resonators, significantly reducing device complexity
Solution Approach 2:
The dynamic liquid crystal system is replaced with a static geometric structure. The wave steering function previously achieved through electric field control of liquid crystal molecules is now achieved through the geometric arrangement and shapes of resonators, eliminating mechanical/electric control complexity
3Device complexity
If resonators are spaced apart in the metasurface structure, then the liquid crystal layer can be positioned between resonators and electrode layer, but discontinuous phase changes occur leading to low reflectivity in desired directions
Solution Approach 1:
The resonators are arranged in homogeneous, continuous patterns without spacing gaps that would cause discontinuities. This homogeneous arrangement ensures continuous phase changes across the metasurface, achieving high reflectivity in desired directions while maintaining the flexibility to position functional layers
4Adaptability or versatility
If the liquid crystal compound is allowed to tilt with voltage application, then beam steering is achieved, but the refractive index varies discontinuously between resonator regions and inter-resonator regions
Solution Approach 1:
The resonators are arranged in continuous, homogeneous patterns that eliminate gaps and discontinuities. This homogeneous structure ensures uniform refractive index distribution across the entire metasurface, achieving stable beam steering without discontinuous variations between resonator and inter-resonator regions
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 enhances the reflectivity of electromagnetic waves in desired directions, increasing the utilization efficiency of electromagnetic waves and allowing for effective wave steering beyond specular reflection.
Implementation Method 1
the phase of electromagnetic waves continuously changes in the arrangement direction of three unit cells adjacent to each other by the continuous change of the refractive index in the liquid crystal layer
Implementation Method 2
In the liquid crystal layer, for example, a rod-like liquid crystal compound 104a is aligned. Hereinafter, the rod-like liquid crystal compound 104a will be simply referred to as the liquid crystal compound 104a.
Implementation Method 3
a reflective plate that is attached to a wall or the like and bends radio waves in any direction is required
Implementation Method 4
In the metasurface structure 100, resonators 100a as microstructures are arranged as in a well-known metasurface structure
Data Source
AI summary
An optical member having a high reflectivity of electromagnetic waves in a desired direction for use in a metasurface structure. The optical member includes, in the following order: a reflective layer; a liquid crystal layer that includes a liquid crystal compound; and a metasurface structure where a plurality of microstructures are arranged, in which an in-plane refractive index of the liquid crystal layer continuously changes according to a region of the metasurface structure where two or more microstructures arranged adjacent to each other are present.