High-Figure-of-Merit Biosensing and Enhanced Excitonic Absorption in an MoS 2 -Integrated Dielectric Metasurface.

Among the transitional metal dichalcogenides (TMDCs), molybdenum disulfide (MoS 2 ) is considered an outstanding candidate for biosensing applications due to its high absorptivity and amenability to ionic current measurements. Dielectric metasurfaces have also emerged as a powerful platform for novel optical biosensing due to their low optical losses and strong near-field enhancements. Once functionalized with TMDCs, dielectric metasurfaces can also provide strong photon-exciton interactions. Here, we theoretically integrated a single layer of MoS 2 into a CMOS-compatible asymmetric dielectric metasurface composed of TiO 2 meta-atoms with a broken in-plane inversion symmetry on an SiO 2 substrate. We numerically show that the designed MoS 2 -integrated metasurface can function as a high-figure-of-merit (FoM=137.5 RIU-1) van der Waals-based biosensor due to the support of quasi-bound states in the continuum. Moreover, owing to the critical coupling of the magnetic dipole resonances of the metasurface and the A exciton of the single layer of MoS 2 , one can achieve a 55% enhanced excitonic absorption by this two-port system. Therefore, the proposed design can function as an effective biosensor and is also practical for enhanced excitonic absorption and emission applications.