Polarization-independent quasi-Bound states In the Continuum based on terahertz all metal metasurfaces
A terahertz(THz)all-metal metasurface with a high Q-factor has been proposed,consisting of four diamond-shaped holes.By altering the size of adjacent diamond-shaped holes,the symmetry of the structure can be broken,resulting in quasi-Bound states In the Continuum(BICs).By changing the polarization angle of the incident wave,the frequency of the excited quasi-BICs remains unchanged,exhibiting polarization-independent characteristics.Simulation results show that,by optimizing structural parameters,when the size deviation is 3 μm,the quasi-BICs achieved an ultra-narrow bandwidth of less than 1 GHz,corresponding to a Q-factor greater than 1 300.Experimental test results show that the fabricated sample(with a deviation of 30 μm)had a measured Q-factor of 40.Compared to circular hole structures,the diamond-shaped hole structure can achieve stronger bound fields due to its sharp corners.The proposed metasurface with polarization-independent quasi-BICs has enormous practical application potential in real-time chemical and biomolecular sensing.
terahertzmetasurfacesall-metalpolarization-independentBound states In the Continuum
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