Observation of coherent folded acoustic phonons propagating in a GaAs/AlAs superlattice by two-color pump-probe spectroscopy
Observation of coherent folded acoustic phonons propagating in a GaAs/AlAs superlattice by two-color pump-probe spectroscopy
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DOI：
10.1103/physrevb.60.8262
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发表时间：
1999-09
影响因子：
3.7
通讯作者：
K. Mizoguchi;M. Hase;S. Nakashima;M. Nakayama
中科院分区：
文献类型：
--
作者：
K. Mizoguchi;M. Hase;S. Nakashima;M. Nakayama
The coherent folded longitudinal acoustic (FLA) phonons in a GaAs/AlAs superlattice have been studied using a two-color pump-probe technique and a designed sample in which the superlattice layer is sandwiched by ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ cladding layers. The two-color pump-probe technique makes it possible to separate regions of generation and detection of coherent phonons, which provides a powerful tool to examine the spatial dynamics of coherent phonons. We have found two types of coherent FLA phonons: the first-order FLA phonons with finite wave vectors $(q\ensuremath{\ne}0)$ and the zone-center mode of the first-order FLA phonons $(q=0).$ When ballistic acoustic phonons are generated near the surface region of the ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ cladding layer and propagate through the superlattice layer, the first-order FLA phonons with $q\ensuremath{\ne}0$ are observed in the superlattice layer. On the other hand, when the FLA phonons are generated within the superlattice layer, the zone-center FLA phonon extending from the superlattice layer is detected near the surface region of the ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ cladding layer.
The coherent folded longitudinal acoustic (FLA) phonons in a GaAs/AlAs superlattice have been studied using a two-color pump-probe technique and a designed sample in which the superlattice layer is sandwiched by ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ cladding layers. The two-color pump-probe technique makes it possible to separate regions of generation and detection of coherent phonons, which provides a powerful tool to examine the spatial dynamics of coherent phonons. We have found two types of coherent FLA phonons: the first-order FLA phonons with finite wave vectors $(q\ensuremath{\ne}0)$ and the zone-center mode of the first-order FLA phonons $(q=0).$ When ballistic acoustic phonons are generated near the surface region of the ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ cladding layer and propagate through the superlattice layer, the first-order FLA phonons with $q\ensuremath{\ne}0$ are observed in the superlattice layer. On the other hand, when the FLA phonons are generated within the superlattice layer, the zone-center FLA phonon extending from the superlattice layer is detected near the surface region of the ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ cladding layer.