Double-layer symmetric gratings with bound states in the continuum for dual-band high-Q optical sensing

• Chaoying Shi,
• Jinhua Hu,
• Xiuhong Liu,
• Junfang Liang,
• Jijun Zhao,
• Haiyan Han and
• Qiaofen Zhu

Beilstein J. Nanotechnol. 2022, 13, 1408–1417, doi:10.3762/bjnano.13.116

• , Hebei 056038, P. R. China 10.3762/bjnano.13.116 Abstract Herein, we theoretically demonstrate that a double-layer symmetric gratings (DLSG) resonator consisting of a low-refractive-index layer sandwiched between two high-contrast gratings (HCG) layers, can host dual-band high-quality (Q) factor

• controlling the cavity length of the structure. Further, the two types of BIC can be converted into quasi-BIC (QBIC) by either changing the spacing between adjacent gratings or changing the distance between the upper and lower gratings. The simulation results show that the dual-band high-performance sensor is

• achieved with the highest sensitivity of 453 nm/RIU and a maximum figure of merit (FOM) of 9808. Such dual-band high-Q resonator is expected to have promising applications in multi-wavelength sensing and nonlinear optics. Keywords: bound states in the continuum; dual band; high quality factor; localized