Efficient Optomechanical Mode-Shape Mapping of Micromechanical Devices

Abstract

Visualizing eigenmodes is crucial in understanding the behavior of state-of-the-art micromechanical devices. We demonstrate a method to optically map multiple modes of mechanical structures simultaneously. The fast and robust method, based on a modified phase-lock loop, is demonstrated on a silicon nitride membrane and shown to outperform three alternative approaches. Line traces and two-dimensional maps of different modes are acquired. The high quality data enables us to determine the weights of individual contributions in superpositions of degenerate modes.

Keywords

• optomechanics
• mode-mapping
• MEMS
• phase-lock loop
• silicon-nitride
• membrane