Investigation on the optical dual-band absorption enhancement for graphene photodetector

In this study, we investigated the optical properties of a defective one-dimensional photonic crystal containing a graphene-embedded microcavity. Numerical and theoretical studies indicated that the strong field localization induced by two defective modes near graphene significantly enhanced the interaction between light and graphene, realizing absorptions of 98.82% and 97.99% at 653 nm and 979 nm, respectively. The addressable tuning of the two defective modes can be achieved by modulating the structure scaling factor according to the scale property of Maxwell's equations. More importantly, by dynamically changing the incident angle or the chemical potential of graphene, the absorption wavelength can be continuously adjusted, and the absorption efficiency can be regulated stepwise. This study can serve as a dynamic block for multichannel optical systems and provide a useful reference for related fields, including detection, sensing, switches, and filters.