Dynamically tunable bound states in the continuum supported by asymmetric Fabry–Pérot resonance
Enduo Gao, Hongjian Li, Chao Liu, Banxian Ruan, Min Li, Baihui Zhang, Zhenbin Zhang
Abstract
The dynamic regulation of quasi-bound states in the continuum (quasi-BIC) is a research hotspot, such as incident angle, polarization angle, temperature, a medium refractive index, and medium position regulation. In this paper, a dual-band ultra-high absorber composed of upper asymmetric graphene strips and lower graphene nanoribbons can generate a symmetry-protected quasi-BIC and Fabry-Pérot resonance (FPR) mode. The band structure further demonstrates the symmetry-protected BIC. Research shows that the absorption system can withstand a relatively wide range of incidence and polarization angles. Interestingly, the quasi-BIC and FPR modes can be modulated by the Fermi levels of the graphene1 and graphene2, respectively, realizing a multifunctional switch with high modulation depth (MD > 94%), low insertion loss (IL < 0.23 dB), and large dephasing time (DT > 4.35 ps). This work provides a new approach for the dynamic regulation of quasi-BIC and stimulates the development of multifunctional switches in the absorber.