Water‐Resistant Subwavelength Perovskite Lasing from Transparent Silica‐Based Nanocavity

Abstract Great research efforts are devoted to exploring the miniaturization of chip‐scale coherent light sources possessing excellent lasing performance. Despite the indispensable role in Si photonics, SiO 2 is generally considered not contributing to the starting up and operation of integrated lasers. Here, this work demonstrates an extraordinary‐performance subwavelength‐scale perovskite vertical cavity laser with all‐transparent SiO 2 cavity, whose cavity is ultra‐simple and composed of only two parallel SiO 2 plates. By introducing a ligand‐assisted thermally co‐evaporation strategy, highly luminescent perovskite film with high reproducibility and excellent optical gain is grown directly on SiO 2 . Benefitting from their high‐refractive‐index contrast, low‐threshold, high‐quality factor, and single‐mode lasing is achieved in subwavelength range of ≈120 nm, and verified by long‐range coherence distance (115.6 µm) and high linear polarization degree (82%). More importantly, the subwavelength perovskite laser device could operate in water for 20 days without any observable degradation, exhibiting ultra‐stable water‐resistant performance. These findings would provide a simple but robust and reliable strategy for the miniaturized on‐chip lasers compatible with Si photonics.