The pump-probe technique is an effective instrument for investigating ultrafast dynamics. It is widely used in fundamental research and application fields, such as Physics, Chemistry and Biology. First introduced is t...The pump-probe technique is an effective instrument for investigating ultrafast dynamics. It is widely used in fundamental research and application fields, such as Physics, Chemistry and Biology. First introduced is the effect process between femtosecond laser and matter. And set forth is the fundamental of ultrafast phenomena and theory foundation of data disposal. Then introduced is the demand of making samples in experiment, experiment equipment, and the theory of strain pulse. We detect transient reflectivity change on surface of GaAs at different delayed time using femtosecond transient reflection spectroscopy. The changing curve consists of three parts： original scattering process of 100 fs, carriers-lattice thermal equilibrium of l. 5 ps and recombination process of 500 los.展开更多
This paper reports an application of an optical fiber sensor in a continuous and in situ failure testing of an E-glass/vinylester top hat stiffener （THS）. The sensor head was constructed from a compact phase-shifted...This paper reports an application of an optical fiber sensor in a continuous and in situ failure testing of an E-glass/vinylester top hat stiffener （THS）. The sensor head was constructed from a compact phase-shifted fiber Bragg grating （PS-FBG）. The narrow transmission channel of the PS-FBG is highly sensitive to small perturbation, hence suitable to be used in acoustic emission （AE） assessment technique. The progressive failure of THS was tested under transverse loading to experimentally simulate the actual loading in practice. Our experimental tests have demonstrated, in good agreement with the commercial piezoelectric sensors, that the important failures information of the THS was successfully recorded by the simple intensity-type PS-FBG sensor.展开更多
基金National Natural Science Foundation of China(50275089)
文摘The pump-probe technique is an effective instrument for investigating ultrafast dynamics. It is widely used in fundamental research and application fields, such as Physics, Chemistry and Biology. First introduced is the effect process between femtosecond laser and matter. And set forth is the fundamental of ultrafast phenomena and theory foundation of data disposal. Then introduced is the demand of making samples in experiment, experiment equipment, and the theory of strain pulse. We detect transient reflectivity change on surface of GaAs at different delayed time using femtosecond transient reflection spectroscopy. The changing curve consists of three parts： original scattering process of 100 fs, carriers-lattice thermal equilibrium of l. 5 ps and recombination process of 500 los.
文摘This paper reports an application of an optical fiber sensor in a continuous and in situ failure testing of an E-glass/vinylester top hat stiffener （THS）. The sensor head was constructed from a compact phase-shifted fiber Bragg grating （PS-FBG）. The narrow transmission channel of the PS-FBG is highly sensitive to small perturbation, hence suitable to be used in acoustic emission （AE） assessment technique. The progressive failure of THS was tested under transverse loading to experimentally simulate the actual loading in practice. Our experimental tests have demonstrated, in good agreement with the commercial piezoelectric sensors, that the important failures information of the THS was successfully recorded by the simple intensity-type PS-FBG sensor.
