在单颗磷化镓纳米天线中全光产生与探测相干声学振动：近 Anapole 激发下的研究
All-Optical Generation and Detection of Coherent Acoustic Vibrations in Single Gallium Phosphide Nanoantennas Probed Near the Anapole Excitation
AI总结：
本文研究单颗磷化镓纳米盘在泵浦-探测下的相干声学振动，发现探测效率在 anapole 态附近最高，其调制幅度可比金等离激元谐振器大约 5 倍，并演示了基底声波发射与纳米结构间机械耦合，为光子-声子信号处理奠定基础。
摘要：
纳米结构高折射率介质作为低损耗光子平台，在波前控制和增强光学非线性方面展现出巨大潜力。然而，它们作为光机械谐振器的潜力仍未得到探索。本工作采用泵浦-探测构型，研究了二氧化硅基底上单个晶体磷化镓纳米盘中的相干声学声子的产生与探测。通过将介质泵浦到其带隙能量以上并在其透明区域进行探测，我们观察到纳米盘的径向呼吸模式，振荡频率约为 10 GHz。我们分析了直径在 300-600 nm 范围内、高度固定为 125 nm 的不同尺寸纳米天线的性能，发现探测效率在基本 anapole 态附近达到最大，与数值模拟一致。通过与参考的金纳米盘和纳米棒等离激元谐振器比较，我们发现介质纳米天线的调制幅度最高约大 5 倍。我们进一步演示了通过下方基底发射声波，以及相距 3 μm 的两个纳米结构之间的机械耦合，为利用介质纳米天线进行光子-声子信号处理奠定了基础。
英文摘要：
Nanostructured high-index dielectrics have shown great promise as low-loss photonic platforms for wavefront control and enhancing optical nonlinearities. However, their potential as optomechanical resonators has remained unexplored. In this work, we investigate the generation and detection of coherent acoustic phonons in individual crystalline gallium phosphide nanodisks on silica in a pump-probe configuration. By pumping the dielectric above its bandgap energy and probing over its transparent region, we observe the radial breathing mode of the disk with an oscillation frequency around 10 GHz. We analyze the performance of nanoantennas of various sizes in the 300-600 nm diameter range at fixed 125 nm height and find that the detection efficiency is maximum near the fundamental anapole state, in agreement with numerical simulations. By comparing with reference gold nanodisk and nanorod plasmonic resonators, we find that the dielectric nanoantennas display a modulation amplitude up to ~5 times larger. We further demonstrate the launching of acoustic waves through the underlaying substrate and the mechanical coupling between two nanostructures placed 3 μm apart, laying the basis for photonic-phononic signal processing using dielectric nanoantennas.
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