Highly coherent organic lasing based on etch-free metasurface.

Metasurfaces supporting bound states in the continuum (BIC) can be leveraged as lasing platforms, offering ultra-compact and highly coherent light sources. Although designs using low-index polymers that do not require etching have been demonstrated and shown to possess remarkably high quality factors for free-space radiation, these have been so far limited to passive designs. Here, we report on highly coherent BIC-based lasing, emerging from etch-free metasurfaces that are directly patterned onto organic supramolecular materials consisting of small-molecule, ionic isolation lattices (SMILES). We observe highly directional lasing with a divergence angle of 0.2°, linewidth of 0.04 nm - limited by the spectral resolution of our measurement setup - and a temporal coherence of 20.4 ± 2.4 ps. The reported performance is a direct consequence of the combination of high-quality metasurface designs with the intrinsic uniformity and stability of SMILES, offering a strategy to realize active metasurfaces and organic molecular lasers, superior to alternative approaches based on solution-processable materials.