Quasi bound states in the continuum in silicon corrugated grating structure for high performance sensor

Abstract

Quasi bound states in the continuum (BICs) with a high quality factor (Q factor) have a promising potential for designing and fabricating novel optoelectronic devices. We propose a silicon corrugated structure and find that the structure supports BICs at the normal incidence. When the incident light deviates from the vertical direction and enters the structure at a small incident angle, the BICs turn to quasi-BICs with a high Q factor. It is shown that the resonant peak shifts obviously as the changing of refractive index of sensing medium by introducing a sensing medium at the incident side. The high performance gas and liquid sensors with ultrahigh figure of merit are obtained. In addition, we discuss the influence of absorption of sensing media and silicon on sensing performance.