Q-factor enhancement of Fano resonance in all-dielectric metasurfaces by modulating meta-atom interactions

We numerically investigated the effects of meta-atom interactions on the Fano resonance in all-dielectric metasurfaces by introducing alternately flipped asymmetric paired bars (APBs) and split asymmetric paired bars (SAPBs). With alternately flipped configurations, the Q-factor of the Fano resonance is significantly enhanced up to one order of magnitude, and the electric field is strengthened by more than twice. Abnormally, the Q-factor increases with gap size in the alternately flipped SAPBs. These are attributed to the destructive interaction among nearest-neighbor dipole resonators. The Q-factor of 108 and Raman enhancement factor of 109 in the gap can be realized with the alternately flipped SAPBs made of Si. Our study provides a way to improve performance of practical devices such as ultrasensitive sensors, nonlinear optics, and quantum emitters.