Browsing by Author "Wang, Y. T."

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Eliminate coherence spike in reflection-type pump-probe measurements
(2009-07-06)
Luo, C. W.
;
Wang, Y. T.
;
Chen, F. W.
;
Shih, H. C.
;
Kobayashi, T.
The coherence spike of femtosecond laser pulses in the reflection-type pump-probe measurements has been systematically studied in the semiconductor (100) InP. By varying the setup of the pump-probe measuring system, i.e. the polarizations of pump and probe pulses, the incident angles of pump and probe beams, and the interval of delay time between pump and probe pulses, the dramatic changes in the strength of coherence spike could be clear observed. Furthermore, the proposed methods to remove the coherence spike from the transient reflectivity curves have been demonstrated in the time-domain measurements. (C) 2009 Optical Society of America
Ultrafast Dynamics in Optimally Doped YBa(2)Cu(3)O(7-delta) Observed with White Light Pump-probe Spectroscopy
(2011-01-01)
Wang, Y. T.
;
Lee, Y. H.
;
Chen, Y. -J.
;
Tang, W. T.
;
Luo, C. W.
The quasiparticle relaxation dynamics in optimally doped (001) YBa(2)Cu(3)O(7-delta) thin films were measured at various temperatures by white light pump-probe technique. The 2D ultrafast spectroscopy with broadband (similar to 200 nm) and high time-resolution (similar to 9 fs) was performed by the non-collinear optical parametric amplifier (NOPA). The relaxation time and the amplitude of the transient transmissivity changes (Delta T/T) are wavelength-dependent. The maximum Delta T/T appears at around 625 nm (similar to 1.98 eV) which corresponds to the transition between the Fermi level and the UHB (upper Hubbard band). Furthermore, the oscillations with similar to 150, similar to 320, similar to 500 cm(-1) have been clearly observed in the Fourier transformed graph of the 2D ultrafast spectroscopy, which are consistent with the phonon modes in Raman-scattering spectra.
Ultrafast Dynamics in Optimally Doped YBa2Cu3O7-delta Observed with White Light Pump-probe Spectroscopy
(2011-01-01)
Wang, Y. T.
;
Lee, Y. H.
;
Chen, Y. -J.
;
Tang, W. T.
;
Luo, C. W.
The quasiparticle relaxation dynamics in optimally doped (001) YBa2Cu3O7-delta thin films were measured at various temperatures by white light pump-probe technique. The 2D ultrafast spectroscopy with broadband (similar to 200 nm) and high time-resolution (similar to 9 fs) was performed by the non-collinear optical parametric amplifier (NOPA). The relaxation time and the amplitude of the transient transmissivity changes (Delta T/T) are wavelength-dependent. The maximum Delta T/T appears at around 625 nm (similar to 1.98 eV) which corresponds to the transition between the Fermi level and the UHB (upper Hubbard band). Furthermore, the oscillations with similar to 150, similar to 320, similar to 500 cm(-1) have been clearly observed in the Fourier transformed graph of the 2D ultrafast spectroscopy, which are consistent with the phonon modes in Raman-scattering spectra.