Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.Howe...Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.展开更多
概述地面数字电视单频网(Single Frequency Network,SFN)增益的概念、SFN覆盖判据及k因子对数正态法(k Log-Normal Method,k-LNM)算法,研究SFN组网前后对数正态分布变量的变化趋势,将SFN增益分为加性增益和统计增益,针对等场强和不等场...概述地面数字电视单频网(Single Frequency Network,SFN)增益的概念、SFN覆盖判据及k因子对数正态法(k Log-Normal Method,k-LNM)算法,研究SFN组网前后对数正态分布变量的变化趋势,将SFN增益分为加性增益和统计增益,针对等场强和不等场强两种场景给出了应用k-LNM计算SFN增益的实例并分析计算结果。研究过程和结果为地面数字电视广播(Digital Television Terrestrial Multimedia Broadcasting,DTMB)SFN组网规划和建设过程中扩大覆盖和降低干扰提供了新的理论依据。展开更多
文摘Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.
文摘概述地面数字电视单频网(Single Frequency Network,SFN)增益的概念、SFN覆盖判据及k因子对数正态法(k Log-Normal Method,k-LNM)算法,研究SFN组网前后对数正态分布变量的变化趋势,将SFN增益分为加性增益和统计增益,针对等场强和不等场强两种场景给出了应用k-LNM计算SFN增益的实例并分析计算结果。研究过程和结果为地面数字电视广播(Digital Television Terrestrial Multimedia Broadcasting,DTMB)SFN组网规划和建设过程中扩大覆盖和降低干扰提供了新的理论依据。
