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

• to different distributions of the localized optical field in the two modes. As seen in Figure 3b and Figure 3c, the optical field of mode 1 is mainly localized near the upper and lower gratings at the same α value, whereas most of the optical field in mode 2 is confined to the cavity. To physically

• BIC also possesses a strong localized optical field. Therefore, the FP-BIC can be perturbed by the variation on the cavity length. To further understand the capability of different cavity lengths of the two modes to confine the localized optical field, the energy ratio of the cavity to the unit cell

• optical field; nonlinear optics; optical sensing; Introduction High quality (Q) factor resonance in nanophotonics has attracted considerable attention in the past decades due to its wide applications in narrow-band filters [1], nonlinear optics [2], optical sensors [3] and lasers [4]. To date, most