Fano resonances generation in pyramidal lithium niobate metasurfaces with vertical symmetry-breaking

Fano resonance exhibits an asymmetric spectral profile with a sharp change between a dip and a peak. However, high quality factor Fano resonance is extremely difficult to be fabricated because of its ultra-sensitivity to geometrical imperfections. Here, we demonstrate the Fano resonances generation in all-dielectric pyramidal lithium niobate metasurface with vertical symmetry-breaking, which does not require tight geometrical tolerances and can be easily fabricated. The quality factor of the generated Fano resonance can reach up to 10(7) due to the reserve of horizontal symmetry. Our work provides a new method of achieving Fano resonances, which can find potential applications in a large variety of prominent optical devices, such as slow-light devices, susceptible sensors and ultrafast switches. Due to the large electro-optic coefficient of lithium niobate and the enhanced Pockels effect in the slow photon system, it has great potential for realizing tunable Fano resonance with extremely low voltage. These tuned Fano resonances, with a low voltage, will find many applications such as high-resolution spectroscopy, biomolecular detection, and tunable laser.