Fano-resonant propagating plexcitons and Rabi-splitting local plexcitons of bilayer borophene in TERS

Optical nanocavity provides an opportunity to deeply study the light–matter interaction with notable findings such as Rabi splitting in strong coupling and Fano resonance weak coupling. Here, we theocratically explore plexcitons of a bilayer (BL) borophene synthesized on Ag (1 1 1) film tip-enhanced Raman scattering (TERS) system, where BL is located between tip substrate, stimulated by recent experimental synthesis [Liu et al., Nat. Mater. 21, 35 (2022)]. In strong-coupling region, negative real part dielectric function manifests; plasmonic properties resulting 310 meV. weak-coupling spectra show typical asymmetry sharp change dip peak (Fano resonance). A balanced gain loss facilitates single-mode lasing parity-time symmetry-broken regime, very narrow half-width ultrahigh enhancement factor up 108. Fano-resonant propagating are observed resonance, which extremely sensitive excitation wavelength. Our results not only deepen physical understanding plasmon–exciton TERS system but also provide way manipulate system.