Low-threshold upconversion plasmonic lasers based on CsPbBr₃ nanoplates

Upconversion lasers offer a robust platform for the new generation of highly integrated nonlinear optoelectronic applications. They are central in addressing the ongoing pursuit of miniaturization, low loss, and high-quality nonlinear light sources required for modern photonic integrated circuits. However, the endeavor to minimize volume and threshold poses inevitable challenges to the anti-Stokes process within upconversion lasers. In this study, we report a potential room-temperature upconversion plasmonic nanolaser utilizing CsPbBr₃ nanoplates. This device exhibits a significant decrease in threshold over a wide volume range while maintaining a high-quality factor. More excitingly, we have successfully fabricated the miniaturized upconversion plasmonic lasers with a thickness as low as 70 nm, breaking down the optical diffraction limit to the deep sub-wavelength regime. Through carefully plotted simulations of two-photon (TP) excitation light fields, we have revealed the intricacies of the plasmon-assisted lasing process. Furthermore, our experiments, which vary the thicknesses of the insulating SiO₂ layer, have unveiled the tunable properties of the TP excitation light confinement intensity and the Purcell effect. These findings open up promising avenues for fine-tuning the performance of plasmonic devices. Our research underscores the efficiency and low-threshold attributes of upconversion plasmonic nanolasers, heralding them as potent candidates for on-chip nonlinear light sources.