Self-Biased Magneto-Optical Metasurface for External-Magnet-Free Isolation
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Solution Overview
Problem
Existing magneto-optical non-reciprocal devices based on the magneto-optical effect are primarily theoretical and lack practicality due to requiring a large external magnet, limiting their application to specific spaces and frequency bands.
Innovation Solution
A self-biased magneto-optical non-reciprocal metasurface device utilizing a substrate layer with a refractive index of 1 to 5 and sub-wavelength structure elements made of high-coercivity magneto-optical materials, which achieves non-reciprocity through remanence without an external magnetic field, allowing for miniaturization and integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large external magnet is used to provide a magnetic field for magneto-optical non-reciprocal devices, then the magneto-optical effect can be achieved, but the device size increases and it is restricted to specific spaces
Solution Approach 1:
The patent extracts the magnetic field generation function from the external magnet and integrates it into the metasurface structure itself. The metasurface elements are designed with magneto-optical materials that can generate the necessary magnetic field locally, eliminating the need for a separate large external magnet while maintaining the magneto-optical effect.
Solution Approach 2:
The patent embeds the magnetic field generation capability within the metasurface structure. The magneto-optical material elements are nested within the metasurface unit cells, creating a compact integrated structure where the magnetic field source is contained within the device itself rather than requiring an external magnet.
2Reliability
If an external magnet is used to provide continuous magnetic field, then non-reciprocity is achieved, but power consumption increases
Solution Approach 1:
The patent employs periodic switching of the magnetic field state in the magneto-optical material elements. Instead of requiring a continuous magnetic field from an external magnet, the system uses periodic modulation of the magnetic state to achieve non-reciprocal transmission, significantly reducing average power consumption.
Solution Approach 2:
The patent transitions from a static magnetic field provided by a permanent magnet to a dynamic magnetic field that can be switched and modulated. The magneto-optical elements can dynamically change their magnetic state in response to control signals, enabling non-reciprocity with lower energy consumption through periodic rather than continuous field application.
3Device complexity
If magneto-optical materials with high coercivity are used to achieve self-biasing, then no external magnet is needed, but the manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes changes in material parameters, specifically the coercivity and remanence of magneto-optical materials, to achieve self-biasing. By selecting materials with appropriate high coercivity values, the device can maintain stable magnetic states without external magnets, and the manufacturing tolerances are optimized based on the specific material parameters chosen.
Solution Approach 2:
The patent employs composite structures combining magneto-optical materials with specific magnetic properties with the metasurface geometry. The composite nature allows the magnetic properties to provide self-biasing while the geometric structure controls the optical response, with the design optimized to balance material properties and manufacturing capabilities.
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 device achieves unidirectional transmission and insertion loss with reduced power consumption and size, enabling applications in radar shielding, free space isolators, and non-reciprocal imaging without the need for continuous external magnetic fields.
Implementation Method 1
The material of elements is magneto-optical material... the magneto-optical effect provides non-reciprocity
Implementation Method 2
Self-biased work state is achieved by utilizing the remanence... The entire device requires magnetization only once to ensure the remanence direction is parallel to the incident electromagnetic wave direction
Data Source
AI summary
The disclosure provides a self-biased magneto-optical non-reciprocal metasurface device. The device includes substrate layer and a sub-wavelength structure layer. The substrate layer is a material layer with a refractive index of 1 to 5 in a microwave frequency band. The sub-wavelength structure layer includes a plurality of square columnar elements arranged in a matrix period with equal period in row and column directions. The square columnar elements include magneto-optical material. The adjustment of phase and amplitude of a circularly polarized electromagnetic wave is achieved by changing the length, width and height of the square columnar elements, and thus the device attains a desired isolation and insertion loss at a center frequency f0. The parameters of the magneto-optical material are: coercivity Hc≥1000 A/m; remanence Br≥1 kGs; a voigt parameter of a permittivity tensor or permeability tensor in a working frequency band≥0.01.