Tuning to a particular acoustic whispering-gallery mode in the GHz range
Tuning to a particular acoustic whispering-gallery mode in the GHz range
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DOI：
10.1121/1.4970080
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发表时间：
2016-11
影响因子：
2.4
通讯作者：
S. Mezil;K. Fujita;Montonobu Tomoda;M. Clark;O. Wright;O. Matsuda
中科院分区：
文献类型：
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作者：
S. Mezil;K. Fujita;Montonobu Tomoda;M. Clark;O. Wright;O. Matsuda
利用亚皮秒光脉冲产生的声表面波（SAW）通常用于无损检测。介质对泵浦光的吸收产生SAW，SAW由延迟的探测光脉冲检测。通过扫描聚焦探测光脉冲的位置和时间延迟，可以成像SAW的时空演化。通常使用的设置显示两个主要约束：泵浦光聚焦到在所有方向上产生SAW的圆形光斑，这不允许控制方向性，并且激光重复率frep将可访问的频率限制为nfrep（n = 1，2，.）。在光盘上的回音壁模式（WGM）的激光激发和检测的情况下，仅某些频率是可检测的，并且反向传播模式不能被单独激发。在这里，我们克服了这些限制，在实验GHz声表面波成像的WGM。为了获得任意频率，我们周期性地调制泵浦光和探测光的强度，并利用这两个同相…
Surface Acoustic Waves (SAWs) generated with sub-picosecond light pulses are commonly used in non-destructive testing. The absorption of pump light by the medium generates SAWs that are detected by delayed probe light pulses. The spatiotemporal evolution of the SAWs can be imaged by scanning the position and time delay of the focused probe light pulses. Commonly used setups show two main constraints: the pump light is focused to a circular spot that generates SAWs in all directions, which does not allow control of directionality, and the laser repetition rate frep limits accessible frequencies to nfrep (n = 1,2,…). In the case of laser excitation and detection of whispering-gallery modes (WGM) on a disc, only certain frequencies are detectable, and counter-propagating modes cannot be separately excited. Here, we overcome these limitations in experimental GHz SAW imaging of WGMs. To access arbitrary frequencies, we periodically modulate in intensity of the pump and probe beams and make use of both in-phase...