High-Q Quasi-Bound States in the Continuum in Terahertz All-Silicon Metasurfaces

Bound states in the continuum (BIC)-based all-silicon metasurfaces have attracted widespread attention recent years because of their high quality (Q) factors terahertz (THz) frequencies. Here, we propose and experimentally demonstrate an BIC metasurface consisting air-hole array on a Si substrate. BICs originated from low-order TE TM guided mode resonances (GMRs) induced by (1,0) (1,1) Rayleigh diffraction metagratings, which were numerically investigated. The results indicate that GMRs Q-factors are easily excited manipulated breaking lattice symmetry through changes position or radius air-holes, while resonance frequencies less sensitive to these changes. measured Q-factor is as 490. high-Q potential applications THz modulators, biosensors, other photonic devices.