[9a-PA3-1~10] 22.1 Joint Session M "Phonon Engineering"

▲ [9a-PA3-4] Detecting sub-terahertz mechanical oscillations by a GaAs MEMS thermal sensor

〇Ya Zhang^1,2, Shaoqing Du², Boqi Qiu², Kazuhiko Hirakawa² (1.Tokyo University of Agriculture and Technology, 2.University of Tokyo)

Keywords:phonon transport, MEMS, phonon interference

In this research, we propose a novel method to perform phonon spectroscopy of the heat transport process. We illuminate a GaAs MEMS suspended beam structure with two light pulses from a femtosecond (fs) laser. The generated phonons by the laser pulses propagate through the GaAs beam, and interfere with each other. We measure the phonon interference signal as the temperature rise on the beam by measuring the frequency shift of the MEMS resonator . If coherent phonon transfers exist in the beam, the temperature rise will have a dependence on the time delay between two light pulses, showing a phonon interference pattern. By performing a Fourier transform for the interference signal, we will obtain the phononic spectrum of the heat transport process. Our preliminary result shows that the temperature rise increases when the two laser pulses have a zero time delay, which is a typical feature of the phonon interference. The proposed method is very promising for realizing the ultra-fast phonon spectroscopy of heat transport process.