期刊
ACS APPLIED NANO MATERIALS
卷 2, 期 4, 页码 1909-1919出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsanm.8b02300
关键词
ZnO nanopowders; random lasing; multiphoton absorption; upconversion; ultrafast pulse; photoluminescence
资金
- National Natural Science Foundation of China [61604055, 61704055, 61874044]
- Program of Shanghai Science and Technology Committee [17142202500]
This study reports ultraviolet picosecond random lasing (RL) based on multiphoton absorption in zinc oxide (ZnO) nanopowders with a mean size of similar to 100 nm under femtosecond optical excitation. Upconversion random lasing is achieved with an excitation wavelength increasing from 600 to 1800 nm, corresponding to a five photon excitation. The RL threshold has a slight positive relationship with excitation wavelength, except for a significant increase with four photon excitation at 1200-1300 nm, demonstrating promising upconversion lasing properties of ZnO nanopowders. A remarkably lower RL threshold is observed at long excitation wavelengths ranging from 1500 to 1800 nm than that for four-photon pumping (1200-1300 nm) processes. Defect states in ZnO are suggested to be the reason that results in the excitation wavelength dependence of random lasing. Transient RL characteristics are investigated using time-resolved photoluminescence measurements, with the RL pulse delay time and pulse width observed to decrease with increasing excitation power, demonstrating typical gain-switching lasing characteristics. The 2.6 ps ultrashort pulse width indicates potential for ZnO in ultrafast upconversion random lasing devices.
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