Dynamics of coherent phonon wave-packet

相干声子波包动力学

• 批准号: 11640318
• 负责人: MIZOGUCHI Kohji
• 金额: $ 1.92万
• 依托单位: Osaka City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640318/
• 关键词: coherent phonon; semiconductor superlattice; phonon wave-pecket; 有限周期; モード対象性の破れ; 運動量保存則の緩和; 交渉性; 同位体Ge超格子; フェムト秒パルスレーザー

Dynamics of coherent phonon wave-packet in time and space was investigated by generating the phonon wave-packet in designed semiconductor superlattices. We specially investigated the phonon dynamics by separating generation and detection regions using various wavelengths of the pump and probe pulses.The coherent folded longitudinal acoustic (FLA) phonons in the GaAs/AlAs superlattices were measured by using a 2-color pump-probe technique. The comparison between results obtained by using 1-color and 2-color pump-probe techniques indicates that the wave-vector of the first-order FLA phonons with finite wave vectors (q≠O) is determined by that of the probe pulses. Moreover, the propagation of the phonon wave-packet can be observed in time by using the difference of the penetration depth for the pump and probe pulses.Generation of high-order coherent confined LO phonon modes was observed in a new class of nonpolar isotope semiconductor superlattices. Only Raman active odd-number-order mode … More s are observable in the pump-probe technique. The spectra taken with the variety of polarization of pump beam show clearly that the generation mechanism of the coherent phonons in nonpolar semiconductor like Ge is stimulated Raman scattering.We have investigated dynamical properties of coherent folded longitudinal acoustic (FLA) phonons generated in GaAs/AlAs superlattices (SLs) with 20, 100 and 195 periods. In the time-domain signals of the SL with 20 periods, the coherent FLA phonon mode with the Raman-inactive B_2 symmetry at the Brillouin zone center, which is not observed in the SLs with more than 100 periods, is detected in addition to the Raman-active modes with the A_1 symmetry at and near the zone center. The appearance of the B_2 mode is caused by the break of the mode symmetry due to the finiteness of the total number of periods. Moreover, it is found that the bandwidths of the coherent FLA phonon modes observed in the Fourier transform spectra depend on the finiteness of periodicity and the wave vector. Less

通过在所设计的半导体超晶格中产生声子波包，研究了相干声子波包在时间和空间上的动力学。我们用不同波长的泵浦和探测脉冲分离产生区和探测区，特别研究了声子动力学。利用双色泵浦-探测技术测量了GaAs/AlAs超晶格中的相干折叠纵向声子。比较了单色和双色泵浦探测技术的结果，结果表明，具有有限波矢的一阶FLA声子的波矢(Q、≠、O)由探测脉冲的波矢决定。此外，利用抽运脉冲和探测脉冲穿透深度的差异，可以及时观察到声子波包的传播。在一类新的非极性同位素半导体超晶格中观察到了高阶相干受限LO声子模的产生。只有拉曼有效的奇数阶模…在泵浦-探测技术中，可以观察到更多的S。从抽运光偏振态的变化可以清楚地看出，在像Ge这样的非极性半导体中，相干声子的产生机制是受激拉曼散射。我们研究了20、100和195个周期的GaAsAlAs超晶格(SLS)中产生的相干折叠纵向声子的动力学特性。在具有20个周期的激光的时间域信号中，除了在区中心及其附近观察到具有A_1对称性的喇曼有源模之外，还检测到了在布里渊区中心具有拉曼非活性B_2对称性的相干FLA声子模，这是在100个以上周期的激光器中没有观察到的。B_2模的出现是由于周期总数的有限性导致了模对称性的破缺。此外，还发现在傅里叶变换谱中观察到的相干Fla声子模的带宽与周期的有限性和波矢有关。较少

项目成果

T. Dekorsy, et al.: "Coherent acoustic phonons in semiconductor superlattices"phys. stat. sol. (b). 215. 425-430 (1999)

T. Dekorsy 等人：“半导体超晶格中的相干声子”phys。

M.Nakajima, et al.: "Coherent confined LO phonons in ^<70>Ge/^<74>Ge isotope superlattices generated by ultrafast pulse laser"Physical Review B. 63. 161304(R)1-161304(R)4 (2001)

M.Nakajima等人：“由超快脉冲激光产生的^ 70 > Ge/^ 74 > Ge同位素超晶格中的相干受限LO声子”物理评论B. 63. 161304(R)1-161304(R)4

H. Takeuchi, K. Mizoguchi, T. Hino and M. Nakayama: "Coherent folded acoustic phonons in GaAs/AlAs superlattices with limited periodicity."Physica. B(in press). (2002)

H. Takeuchi、K. Mizoguchi、T. Hino 和 M. Nakayama：“GaAs/AlAs 超晶格中具有有限周期性的相干折叠声子。”物理学。

S.Nakajima,K.Mizoguchi,K.Morita,K.Itoh,H.Harima, and S.Nakashima: "Comparison of coherent and incoherent LO phonons in 70Ge/74Ge superlattices"J.Lumin.. 87-89. 942-944 (2000)

S.Nakajima、K.Mizoguchi、K.Morita、K.Itoh、H.Harima 和 S.Nakashima：“70Ge/74Ge 超晶格中相干和非相干 LO 声子的比较”J.Lumin.. 87-89。

K.Mizoguchi,F.Miyamaru,M.Nakajima,M.Hase, and S.Nakashima: "Study of coherent LO phonon-plasmon coupled modes by double pulse excitation"J.Lumin.. 87-89. 939-941 (2000)

K.Mizoguchi、F.Miyamaru、M.Nakajima、M.Hase 和 S.Nakashima：“双脉冲激发相干 LO 声子-等离子体耦合模式的研究”J.Lumin.. 87-89。