腾讯会议：160-975-699，会议密码：261012

邀请人：赵继民 研究员

联系人：万源 研究员

汪非凡 副研究员

田春璐 ltian@iphy.ac.cn

主办方：中国科学院物理研究所、松山湖材料实验室

报告人简介

Prof. Andrea V. Bragas is Full Professor of Physics at the University of Buenos Aires and Principal Researcher at CONICET, Argentina, where she leads the Laboratory Quantum Electronics. She received her PhD from the University of Buenos Aires and carried out postdoctoral research at the University of Michigan. Her research focuses on ultrafast optics, nanophotonics, and nanomechanics, with particular emphasis on light-matter interaction at the nanoscale, coherent acoustic dynamics, plasmonic and dielectric nanostructures, and metasurfaces.

She has led numerous national and international research projects and collaborations in ultrafast nanoscience and nanophotonics. Her distinctions include, among others, the Georg Forster Research Award from the Alexander von Humboldt Foundation.

报告摘要

Ultrafast optical excitation provides a powerful route to generate, manipulate, and probe coherent mechanical motion at the nanoscale. Optical nanoantennas concentrate electromagnetic energy into subwavelength volumes and, under femtosecond excitation, efficiently drive GHz mechanical modes. Through elastic coupling to the surrounding medium, these localized vibrations can also launch propagating acoustic waves, converting optical energy into mechanical energy and transporting it away from the excitation region.

In this talk, I will discuss different manifestations of this optoacoustic conversion, from the generation, focusing, and remote detection of hypersonic surface acoustic waves to coherent acoustic propagation in low-dimensional materials. I will show how geometry, optical response, mechanical modes, and substrate coupling control the efficiency and directionality of mechanical energy flow, and how collective responses in metasurfaces offer additional degrees of freedom for tailoring coherent nanoscale motion. More broadly, these light-driven strain fields can couple mechanical energy to other degrees of freedom and remotely actuate surface phenomena, with potential applications ranging from magnetization dynamics to nanoscale chemical and catalytic processes.

References:

[1] A. V. Bragas et al., "Nanomechanics with plasmonic nanoantennas: ultrafast and local exchange between electromagnetic and mechanical energy," J. Opt. Soc. Am. B 40, 1196–1211 (2023).
[2] R. Berté et al., "Acoustic far-field hypersonic surface wave detection with single plasmonic nanoantennas," Phys. Rev. Lett. 121, 253902 (2018).
[3] H. D. Boggiano et al., "All-Optical Generation and Detection of Coherent Acoustic Vibrations in Single Gallium Phosphide Nanoantennas Probed near the Anapole Excitation," Nano Lett. 25, 1351–1357 (2025).
[4] M. Aversa et al., "Coherent Acoustic Phonons in Supported and Suspended MoS₂ Nanocavities," ACS Photonics 13, 320–326 (2026).