Open AccessInfluence of long lifetime absorption process on the measurement of ultrafast carrier dynamics
Author(s) -
Wang Wen-Fang,
Ke Chen,
Wu Jing-Da,
Jin Wen,
Tianshu Lai
Publication year - 2011
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.60.117802
Subject(s) - femtosecond , ultrashort pulse , photodetector , materials science , waveform , absorption (acoustics) , spectroscopy , ultrafast laser spectroscopy , optics , wavelength , phase (matter) , relaxation (psychology) , optoelectronics , physics , laser , psychology , social psychology , quantum mechanics , voltage
The wavelength dependence of ultrafast relaxation dynamics of photoexcited carriers in bulk GaAs is studied using femtosecond time-resolved pump-probe transmission spectroscopy under the same photoexcited carrier concentration and the ratio of pump to probe in intensity. Negative and oscillating time-delayed signals are observed at central wavelengths of 760 nm and 780 nm and judged to be incorrect physically by comparson with a simulated computation result. It is found by waveform analysis that they are caused by the phase reversal of the output waveforms from a photodetector, while the phase reversal originates from a long lifetime absorption process existing in GaAs sample. It is pointed out that the phase reversal of the waveform can be corrected by raising the ratio of pump to probe in intensity at the photodetector, so that right transient traces can be obtained. However, raising the ratio is incompatible with the viewpoint that the scattered contribution to the photodetector from pump light should be filtered as much as possible. This result has an important reference value for the acquisition of correct ultrafast dynamics using time-resolved pump-probe spectroscopy.