Strong coupling between excitons and quasi-bound states in the continuum mode with stable resonance wavelength in the near-infrared region

Strong coupling between photons and excitons gives rise to Rabi splitting and hybridized states. These exhibit spectral anticrossing behavior and ultrafast energy exchange, demonstrating remarkable nanophotonic properties and offering exciting application possibilities. Herein, we propose a metasurface based on dimeric MoTe2 nanodisks for flexible control of the strong coupling between quasi-bound states in the continuum (QBIC) and excitons in the near-infrared region. It was found that introducing a gap perturbation transforms the BIC into a QBIC with a stable resonance wavelength, and the gap width can be used to customize its Q-factor. We confirmed that the upper limit of the Q-factor for achieving strong coupling is 500 in this QBIC metasurface system. It is noted that the wavelength of the QBIC mode and exciton peak are stable, so the coupling strength can be easily adjusted using the disturbance parameters. Moreover, significant Rabi splitting and typical anticrossing behavior were observed when the thickness and radius of the dimeric MoTe2 nanodisks were varied. The Rabi splitting value was 170 meV for f 0 = 1.0. This work provides a useful solution for strong coupling in the near-infrared region, which may pave the way toward tunable near-infrared exciton polariton devices with high compatibility.