Subdiffraction spatial mapping of nanomechanical modes using a plasmomechanical system
Brian Roxworthy, Sreya Vangara, Vladimir A. Aksyuk
Plasmomechanical systems - formed by introducing a mechanically compliant gap between metallic nanostructures - produce large optomechanical interactions that can be localized to deep subwavelength volumes. This unique ability opens a new path to study optomechanics in nanometer-scale regimes inaccessible by other methods. Here, we demonstrate that localized motion transduction enabled by plasmomechanics can be used to spatially map the displacement modes of a vibrating nanomechanical system with a resolution approximately twice that of a wide-field microscope. We show that white light illumination can be used for transduction instead of a monochromatic laser, and develop a semi-analytical model matching the changes in optomechanical coupling constant and motion signal strength observed in a broadband transduction experiment. Our results represent a new functionality for the growing field of plasmomechanical systems and may benefit applications in wafer-scale sensing and optomechanical modulation.