Fig. 2: Polariton condensation at BICs in an organic metasurface.
a–d Angle-resolved photoluminescence spectra from an organic metasurface under non-resonant pulsed excitations with different energy densities, 0.23 μJ cm−2 (a), 0.30 μJ cm−2 (b), 0.38 μJ cm−2 (c), and 0.56 μJ cm−2 (d). a–c show the polariton condensation at BIC2, while d exhibits the scattering of polariton condensates from the BIC2 to mode 1. The two bright emission lobes around the Γ point (θ = 0) (b, c) are a typical characteristic of polariton BICs. e Evolution of the photoluminescence (PL) spectrum from the broad band to sharp peak with the pump fluence, revealing a polariton condensation threshold of 0.30 μJ cm−2 and an increase in temporal coherence of polariton emission. f Polariton emission intensities (blue) and full widths at half maximum (FWHMs) (red) near θ = 0 versus the pump fluences. g Energy blueshift with respect to the BIC polariton emission energy as a function of the pump fluence, which is a typical result of polariton–exciton/polariton interactions.
