Ultrahigh Q-Guided Resonance Sensor Empowered by Near Merging Bound States in the Continuum

Bound states in the continuum (BICs) have attracted a lot of interest field nanophotonics, and provide an important physical mechanism to realize high quality (Q) factor resonance. However, practice, manufacturing error will greatly affect Q factor. In this paper, we propose asymmetric metasurface supporting near merging BIC under normal incidence. Such can achieve higher (>107) than common structures (Q ~ 105) with same degree asymmetry structure. Moreover, BICs also show surface sensitivity other resonant modes. Our work provides promising approach for realization high-performance biosensing platform.