Asia Light Conference in Singapore

Optical manipulation of micro-objects on solid surfaces is challenging due to strong adhesion and friction forces, which dwarfs the optical force considerably by several orders of magnitude. By exploiting light-induced elastic waves, we have recently proposed a solution to this conundrum. Gold micro-plates were actuated on untreated micro-fiber surfaces by using nanosecond light pulses, exhibiting versatile locomotion modes, including rotation, translation, in-plane pose transition and spiral motion, or alternatively, by using modulated continuous-wave light, exhibiting swing-like motions with frequency-dependent mechanical mode profiles. The new actuation mechanism, featuring interactions between elastic waves and their induced friction force, was unveiled. Besides, since elastic waves are excited by optical absorption, potential issues associated with thermal effects (such as thermal damage and melting) have been addressed by exploiting two-dimensional topological-insulator (TI) Sb2Te3 plates adopting the similar plate-fiber systems. Specifically, in the high-power regime, the actuation behavior of the TI plates is remarkably different from that in the low-power regime dominant by the elastic-wave-driven mechanism. Upon ablation and melting, liquid-like motion can be observed, enabled by the Marangoni effects, which highlights the possibility of utilizing phase transition and interface energy profiles to achieve actuation. Moreover, the actuation scheme can be extended to solid environments beyond the fiber side-face to more generalized planer substrates. Specifically, both in-plane and out-of-plane locomotion of adhered microplates can be induced with inputs of nanosecond laser pulses in a vertical optical path set-up, demonstrating the general applicability of the elastic wave-driven mechanism. We envision that the proposed technique, on one hand, could inspire future developments in optical manipulation on solid interfaces through various heat-mediated routes, and, on the other hand, can be integrated into optical chips for many unique applications, such as mobile, reconfigurable optical switches and modulators.

Dr. Min Qiu, a recipient of the The National Science Fund for Distinguished Young Scholars, Director-at-large on the Board of Directors of Optica, SPIE Fellow, IEEE Fellow, CSOE  Fellow, COS Fellow, and CIE Fellow. He received his Bachelor of Science degree in 1995 and got Ph.D. degree in condensed matter physics from Zhejiang University in 1999, and then he got his Ph.D. degree in electromagnetic theory from the Royal Institute of Technology (KTH), Sweden, in 2001, and he was appointed as an assistant professor at the KTH in the same year, then he was promoted to associate professor in 2005, and full professor of photonics in 2009. He was awarded the "Future Research Leader" grant by the Swedish Strategic Research Foundation, and the Senior Researcher Specialized Grant by the Swedish National Foundation for Scientific Research, etc. He was appointed as a professor in the College of Optical Science and Engineering, Zhejiang University in 2010, and was the director of the State Key Laboratory of Modern Optical Instrumentation, Zhejiang University. He joined Westlake University in 2018, and he works as Guoqiang Chair Professor and Vice President presently. His main research interest is micro-nano optoelectronics, including micro-nano fabrication technology and instrumentation, micro-nano photonics theory and optoelectronic devices, key theories and technologies for smart applications, etc. He once led the National Key Research and Development Program of Nanotechnology and the National Key Research Instrumentation Project (free application category) in 2017 and 2020 respectively as the project leader. In July 2022, he was awarded the first prize of the 2021 Zhejiang Provincial Natural Science Award.