Dynamic visualization of surface acoustic waves on a two-dimensional phononic crystal
Dynamic visualization of surface acoustic waves on a two-dimensional phononic crystal
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DOI：
10.1103/physrevb.80.014301
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发表时间：
2009-07-01
影响因子：
3.7
通讯作者：
Lang, Udo
中科院分区：
文献类型：
--
作者：
Profunser, Dieter M.;Muramoto, Eiji;Lang, Udo
利用脉冲超短光激励和检测技术，在频率高达1 GHz的二维空间和真实的时间内，对表面声波在由正方形晶格孔组成的二维声子晶体上的传播进行了成像。通过时空傅立叶变换得到的声学色散关系示出了在平行于声子晶体轴行进的表面波的区域边界处的阻带的开口。我们检测到明显的布洛赫谐波以上的阻带，并揭示在不同频率的空间模式分布。我们还观察到声子准直频率的恒定频率的表面成为正方形的形状。
Surface acoustic wave propagation on a microscopic two-dimensional phononic crystal consisting of a square lattice of holes is imaged in two dimensions and in real time at frequencies up to 1 GHz by means of pulsed ultrashort optical excitation and detection. The acoustic dispersion relation obtained by spatiotemporal Fourier transforms shows the opening of stop bands at the zone boundaries for surface waves traveling parallel to the phononic crystal axes. We detect pronounced Bloch harmonics above the stop band, and reveal the spatial mode distributions at different frequencies. We also observe phonon collimation for frequencies at which the constant-frequency surfaces become square in shape.