报告人：物理学院 梁彬 教授
题目：Manipulation of orbital angular momentum (OAM) for sound
摘要：The existing wave-steering devices generally control acoustic beams carrying only linear momentum. But acoustic vortices imprinted with OAM obviously opens new degree of freedom to control wavefront, with wide applications such as in the design of acoustic “screwdrivers” capable to generate a rotation torque to rotate objects contactlessly. To overcome the drawbacks of the traditional methods for producing acoustic OAM, we have designed and fabricated an acoustic vortex emitter with MACS that utilize diffraction effect to generate vortex beam, with broadband functionality and stable topological charge. Based on this, we further propose a new mechanism for producing acoustic OAM by converting acoustic resonances to OAM. As an implementation, we have designed and fabricated a thin planar device with high efficiency to verify our scheme. In comparison with existing ways for OAM production by phased spiral sources that need sophisticated electronic control and by physically spiral sources that need screw profiles and may also have a bulky size, our acoustic resonance-based OAM production bears the advantages of high efficiency, planar profile, compact size, no spiral structure and can be freely tuned to produce different orders of OAM.
Appl. Phys. Lett. 108, 203501 (2016)
Phys. Rev. Lett. 117, 034301 (2016).
报告人简介：梁彬： 2002 年与2007年分别获得南京大学电子系学士与博士学位； 2007 年7月起在南京大学电子系任教，2014年底起任南京大学物理学院教授。获得首批国家优秀青年科学基金资助，入选南京大学登峰人才B计划及教育部新世纪优秀人才计划。主要研究方向为声学人工材料中的反常声学现象与操控机理，已在Nature Materials（1篇）及PRL（3篇）等国际期刊发表论文50余篇。