Whispering gallery mode micro-lasing in CsPbI3 quantum dots coated on TiO2 microspherical resonating cavities

Whispering gallery mode (WGM) lasing in CsPbI3 quan-tum dots (QDs) coated on TiO2 spherical microcavities is demonstrated. The photoluminescence emission from a CsPbI3-QDs gain medium strongly couples with a TiO2 microspherical resonating optical cavity. Spontaneous emis-sion in these microcavities switches to a stimulated emission above a distinct threshold point of 708.7 W/cm2. Lasing intensity increases three to four times as the power density increases by one order of magnitude beyond the threshold point when the microcavities are excited with a 632-nm laser. WGM microlasing with quality factors as high as Q-1195 is demonstrated at room temperature. Quality fac-tors are found to be higher for smaller TiO2 microcavities (-2 mu m). CsPbI3-QDs/TiO2 microcavities are also found to be photostable even after continuous laser excitation for 75 minutes. The CsPbI3-QDs/TiO2 microspheres are promising as WGM-based tunable microlasers.(c) 2023 Optica Publish-ing Group