Graphene-based fine tuning of Fano resonance transmission of quasi-bound states in the continuum

Quasi-bound state in the continuum (BIC) has significant potential because it supports an ultra-high quality factor (Q-factor). Here, we propose a graphene-embedded subwavelength grating that supports quasi-BIC for tuning very sharp Fano resonance transmission. The strongly enhanced light-graphene interaction from the quasi-BIC enables fine variation of the transmission at the resonant wavelength. The Q-factor of quasi-BIC significantly decreases as the Fermi level of graphene increases. We also propose a low-energy consumption THz-wave modulator using this scheme. The designed modulator shows approximately 100% modulation depth with a Fermi level shift of only E-F = 90 meV. (C) 2022 Optica Publishing Group under the terms of the Optics Open Access Publishing Agreement