Tunable optomechanical devices at the nano scale

23/11/2017 @ 11:00 AM – 12:30 PM Asia/Singapore Timezone
S16 Level 6 – Theory conference room

Speaker: Guangya Zhou
Affiliation: Department of Mechanical Engineering, National University of Singapore
Abstract Details: In this talk, I will discuss tunable nanophotonic resonators integrated with on-chip nanoelectromechanical systems (NEMS). Photonic nano resonator or nano cavity has attracted much attention and becomes increasingly important to a range of nanophotonic applications, including efficient and ultra-compact lasers, nano scale wavelength-selective add/drop multiplexers, optical filters, and high-sensitive sensors. Making nanophotonic resonators tunable is attractive, as tunable nano resonators can provide not only greater flexibility in a dynamic photonic system and but also post-process compensation capability for fabrication imperfections. Tuning nanophotonic resonators with NEMS offers outstanding advantages including low power consumption, large tuning range, absence of exotic materials, and compatible with silicon micro/nano-fabrication processes. I will introduce the NEMS tuning approaches we developed for such resonators, these include: 1) Resonance tuning through cavity evanescent field perturbation using a NEMS-driven dielectric nano probe, 2) Resonance wavelength splitting/shifting/tuning of coupled nano resonators through NEMS-induced coupling strength variation, 3) Resonance tuning by resonator’s nano-deformation driven by NEMS. In addition to tunable nanophotonic devices, I will also discuss the optomechanical interactions at the nano scale. These include demonstration / measurement of significant bipolar optical gradient forces produced by two coupled photonic crystal nanobeam cavities, observation of various “optical spring” effects in coupled nanophotonic cavities where optical fields affect the resonant frequencies of nanomechanical resonators, observation of coherent optomechanical oscillations in coupled nanobeam photonic cavities with a mechanical Q factor over a million, and mechanical mode hoping effect where optomechanical oscillation switches from one mode to the other due to mode competition.

About the Speaker:  A/Prof. Guangya Zhou (Department of Mechanical Engineering, National University of Singapore) Prof. Zhou received the B.Eng. and Ph.D. degrees in optical engineering from Zhejiang University, Hangzhou, China, in 1992 and 1997, respectively. He joined the Department of Mechanical Engineering, National University of Singapore (NUS) in 2005 as an assistant professor. And from 2012, he is an associate professor at the same department. His research interests include optical MEMS scanners, MEMS spectrometers and hyperspectral imagers, optical MEMS based ultra-compact endoscope probes, silicon nanophotonics, NEMS tunable photonic crystals, and nano scale optomechanics. He has published over a hundred research papers in peer-reviewed international journals in his field. He is also the main inventor of the miniature solid tunable lens and aperture technology, which was successfully licensed to a NUS start-up company.