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It is measured that upconversion fluorescent intensity of a new molecule is proportional to the quartic of excitation density. This demonstrates that it is a four-photon absorption process. Furthermore, at high-density ultrashort pulse laser pumping, an emission appears to satisfy four criteria of lasing, including the highly directional emission,the short emission duration, the spectral narrowing, and changing to linear output/input relationship above a threshold. The experimental results demonstrate that the four-photon-process-induced amplified spontaneous emission occurs.