晶格振动的超快光谱调控

发布时间：2018-07-31 15:43

【摘要】：采用飞秒激光抽运脉冲激发了Bi_2Te_3薄膜频率为1.856 THz的声子相干振动,并用探测光测量得到了其阻尼振动信号.结合Raman光谱,确定该振动为A~1_(1g)对称振动模式的相干光学声子.为了实现该模式振动的调控,在抽运光路上安装了脉冲整形器,进而控制生成具有不同时间间隔和能量比的两束脉冲激光.研究表明,当两束脉冲的间隔时间为相干光学声子振动半周期的奇数倍时,调整两束脉冲的能量比值,可以实现A~1_(1g)模式振动的完全消除.继而将两束脉冲的能量比值保持不变,得到了振幅随间隔时间的变化曲线,与理论分析符合.结果进一步证实了用超快光谱调控特定晶格振动的可行性,从而为研究材料内部超快能量传递过程提供了有效手段.
[Abstract]:The coherent phonon vibration of Bi_2Te_3 film with frequency of 1.856 THz is excited by femtosecond laser pumped pulse, and the damping vibration signal is obtained by detecting light. In combination with the Raman spectrum, the vibration is determined to be a coherent optical phonon in the symmetric vibration mode of Agni _ (1g). In order to realize the control of the mode vibration, a pulse shaping device is installed on the pump path to control the generation of two pulsed lasers with different time intervals and energy ratios. It is shown that when the interval time between two pulses is odd times that of the half-period of coherent optical phonon vibration, the energy ratio of the two pulses can be completely eliminated by adjusting the energy ratio of the two pulses. Then, the energy ratio of the two pulses is kept constant, and the variation curve of the amplitude with the interval is obtained, which is in agreement with the theoretical analysis. The results further confirm the feasibility of using ultrafast spectrum to regulate the specific lattice vibration, which provides an effective means for studying the ultrafast energy transfer process in the material.
【作者单位】：东南大学机械工程学院江苏省微纳生物医疗器械设计与制造重点实验室;普渡大学机械工程学院;
【基金】：国家自然科学基金(批准号:51476033)资助的课题~~
【分类号】：TB383

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