Pulse-doubling perovskite nanowire lasers enabled by phonon-assisted multistep energy funneling

Laser pulse multiplication from an optical gain medium has shown great potential in miniaturizing integrated optoelectronic devices.Perovskite multiple quantum wells(MQWs)structures have recently been recognized as an effective gain media capable of doubling laser pulses that do not rely on external optical equipment.Although the light amplifications enabled with pulse doubling are reported based on the perovskite MQWs thin films,the micronanolasers possessed a specific cavity for laser pulse multiplication and their corresponding intrinsic laser dynamics are still inadequate.Herein,a single-mode double-pulsed nanolaser from self-assembled perovskite MQWs nanowires is realized,exhibiting a pulse duration of 28 ps and pulse interval of 22 ps based on single femtosecond laser pulse excitation.It is established that the continuous energy building up within a certain timescale is essential for the multiple population inversion in the gain medium,which arises from the slowing carrier localization process owning to the stronger exciton–phonon coupling in the smaller-n QWs.Therefore,the double-pulsed lasing is achieved from one fast energy funnel process from the adjacent small-n QWs to gain active region and another slow process from the spatially separated ones.This report may shed new light on the intrinsic energy relaxation mechanism and boost the further development of perovskite multiple-pulse lasers.

Superior single-mode lasing in a self-assembly CsPbX3 microcavity over an ultrawide pumping wavelength range

All-inorganic perovskite micro/nanolasers are emerging as a class of miniaturized coherent photonic sources for many potential applications,such as optical communication,computing,and imaging,owing to their ultracompact sizes,highly localized coherent output,and broadband wavelength tunability.However,to achieve singlemode laser emission in the microscale perovskite cavity is still challenging.Herein,we report unprecedented single-mode laser operations at room temperature in self-assembly Cs Pb X3 microcavities over an ultrawide pumping wavelength range of 400–2300 nm,covering one-to five-photon absorption processes.The superior frequency down-and upconversion single-mode lasing manifests high multiphoton absorption efficiency and excellent optical gain from the electron–hole plasma state in the perovskite microcavities.Through direct compositional modulation,the wavelength of a single-mode Cs Pb X3 microlaser can be continuously tuned from blue-violet to green(427–543 nm).The laser emission remains stable and robust after long-term high-intensity excitation for over 12 h(up to 4.3×107 excitation cycles)in the ambient atmosphere.Moreover,the pump-wavelength dependence of the threshold,as well as the detailed lasing dynamics such as the gain-switching and electron–hole plasma mechanisms,are systematically investigated to shed insight into the more fundamental issues of the lasing processes in Cs Pb X3 perovskite microcavities.