Seven-Photon-Excited Upconversion Lasing at Room Temperature

摘要

In contrast to conventional harmonic generation, realized using nonlinearrncrystal, the multiphoton-excited (MPE) laser has critical applications in fluorescencernimaging probe and biological photonics. Here, lasing emission fromrna crystal plate under 7-photon excitation at room temperature is reportedrnfor the first time, which is the highest order MPE lasing reported up to date.rnMoreover, MPE lasing spikes and high-order harmonic peaks are observedrnsimultaneously. The saturation behavior of harmonic generation andrnabnormal fluorescence enhancement identify that the interaction of photon–rnelectron in 7-photon-excited lasing transits from photon-excited to a morernfield-driven regime. The results may pave the way for short wavelength laserrnby taking advantage of the processability and larger scale of solid crystals.