Matsuda Osamu, Koga Hiroaki, Nishita Hiroki, Tomoda Motonobu, Otsuka Paul H, Wright Oliver B
Faculty of Engineering, Hokkaido University, Nishi 8, Kita 13, Kita-ku, Sapporo, Hokkaido, 060-8628, Japan.
Hokkaido University, Nishi 5, Kita 8, Kita-ku, Sapporo, Hokkaido, 060-0808, Japan.
Photoacoustics. 2023 Mar 5;30:100471. doi: 10.1016/j.pacs.2023.100471. eCollection 2023 Apr.
We exploit a time-resolved ultrafast optical technique to study the propagation of point-excited surface acoustic waves on a microscopic two-dimensional phononic crystal in the form of a square lattice of holes in a silicon substrate. Constant-frequency images and the dispersion relation are extracted, and the latter measured in detail in the region around the phononic band gap. Mode conversion and refraction at the interface between the phononic crystal and surrounding non-structured silicon substrate is studied at constant frequencies. Symmetric phonon beam splitting, for example, is shown to lead to a striking Maltese-cross pattern when phonons exit a square region of phononic crystal excited near its center.
我们利用一种时间分辨超快光学技术，来研究点激发表面声波在硅衬底上呈方形孔晶格形式的微观二维声子晶体上的传播。提取了恒定频率图像和色散关系，并在声子带隙附近区域详细测量了后者。在恒定频率下研究了声子晶体与周围非结构化硅衬底之间界面处的模式转换和折射。例如，当声子从在其中心附近激发的方形声子晶体区域射出时，对称声子束分裂会导致出现显著的马耳他十字图案。
