- 公益社団法人 日本表面科学会
- 表面科学 (ISSN:03885321)
- vol.19, no.2, pp.64-71, 1998-02-10 (Released:2009-08-07)
Coherent phonons can be generated in solids by ultra-short pulse laser excitation. Here we report observation of coherent phonon oscillations in the time domain using reflection type pump-probe techniques and discuss the phonon dynamics. An A1g phonon mode was observed for Bi, showing an exponentially decaying oscillation. Temperature dependence of the phonon frequency and the decay rate agrees with the result of Raman measurements. This indicates that the decay process of the coherent phonon is dominated by an anharmonic decay route of energy relaxation. The coherence of phonons in time domain was examined using a double-pulse excitation technique. The oscillation amplitude of the A1g mode in Bi enhances when the pulse separation time is equal to the period of the phonon oscillation, and vanishes when the separation time is adjusted to half integral multiples of the period. We present furthermore the results on coherent folded acoustic modes in GaAs/AlAs superlattices.