1] NSF Nanoscale Science and Engineering Center (NSEC), University of California, Berkeley, 3112 Etcheverry Hall, Berkeley, California 94720, USA [2].
NSF Nanoscale Science and Engineering Center (NSEC), University of California, Berkeley, 3112 Etcheverry Hall, Berkeley, California 94720, USA.
Nat Commun. 2014 Jun 4;5:4042. doi: 10.1038/ncomms5042.
Coherent acoustic phonons modulate optical, electronic and mechanical properties at ultrahigh frequencies and can be exploited for applications such as ultratrace chemical detection, ultrafast lasers and transducers. Owing to their large absorption cross-sections and high sensitivities, nanoplasmonic resonators are used to generate coherent phonons up to terahertz frequencies. Generating, detecting and controlling such ultrahigh frequency phonons has been a topic of intense research. Here we report that by designing plasmonic nanostructures exhibiting multimodal phonon interference, we can detect the spatial properties of complex phonon modes below the optical wavelength through the interplay between plasmons and phonons. This allows detection of complex nanomechanical dynamics by polarization-resolved transient absorption spectroscopy. Moreover, we demonstrate that the multiple vibrational states in nanostructures can be tailored by manipulating the geometry and dynamically selected by acousto-plasmonic coherent control. This allows enhancement, detection and coherent generation of tunable strains using surface plasmons.
相干声学声子在超高频下调节光学、电子和机械性能，可用于超痕量化学检测、超快激光器和传感器等应用。由于纳米等离子体激元共振器具有较大的吸收截面和较高的灵敏度，因此可用于产生高达太赫兹频率的相干声子。产生、检测和控制这种超高频声子一直是研究的热点。在这里，我们报告说，通过设计表现出多模声子干涉的等离子体纳米结构，我们可以通过等离子体和声子的相互作用来检测低于光学波长的复杂声子模式的空间特性。这使得通过偏振分辨瞬态吸收光谱来检测复杂的纳米力学动力学成为可能。此外，我们证明通过声子-等离子体相干控制可以操纵几何形状并动态选择来调整纳米结构中的多个振动状态。这使得可以使用表面等离激元增强、检测和相干产生可调应变。
