Tailoring total absorption in a graphene monolayer covered subwavelength multilayer dielectric grating structure at near-infrared frequencies

We numerically demonstrate 100% light absorption at near-infrared frequencies via a subwavelength multilayer dielectric grating (SMDG) structure covered by a graphene monolayer. Without using plasmonic response, the total absorption is associated with critical coupling, which is enabled by the synergetic effect of the guided resonance and photonic bandgap of the system. Moreover, calculation results demonstrate that critical coupling can be tuned by varying the SMDG structural parameters or simply modulating the gate voltage on the graphene monolayer, as a result to flexibly control the absorption of the system. Furthermore, the enhanced resonance modes are not local, which can be longitudinally coupled deep into the SMDG, effectively facilitating the light-matter interaction. This control over total absorption offered by our design may hold potential in engineering many ultra-compact and high-performance optoelectronic devices. (C) 2017 Optical Society of America