Whispering gallery mode micro-lasing in CsPbI quantum dots coated on TiO microspherical resonating cavities.

Whispering gallery mode (WGM) lasing in CsPbI quantum dots (QDs) coated on TiO spherical microcavities is demonstrated. The photoluminescence emission from a CsPbI-QDs gain medium strongly couples with a TiO microspherical resonating optical cavity. Spontaneous emission in these microcavities switches to a stimulated emission above a distinct threshold point of 708.7 W/cm. 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 factors are found to be higher for smaller TiO microcavities (∼2 µm). CsPbI-QDs/TiO microcavities are also found to be photostable even after continuous laser excitation for 75 minutes. The CsPbI-QDs/TiO microspheres are promising as WGM-based tunable microlasers.