Nanomechanical motion transduction with a scalable localized gap plasmon architecture
Brian J. Roxworthy, Vladimir Aksyuk
Measurement of motion is at the core of scientific advance. From the early Greeks mapping the motion of celestial bodies to molecular analysis, development of increasingly precise motion detection has revolutionized our understanding of the natural world.  Nowadays, chip-scale devices coupling light with mechanical motion are ubiquitous, finding applications from spatial light modulators in movie theaters, telecommunications and adaptive optics for astronomy, [2,3] to atomic-scale mass sensing and sensitive optical readout of micromechanical sensors such as atomic force microscopy cantilevers. [4-6] Strong interactions achieved in dielectric cavity optomechanical devices have pushed the boundaries of light-motion interaction, revealing remarkable effects such as observation of non-classical mechanical behavior.  Despite such profound impact, certain nanomechanical interactions are inaccessible to dielectric devices due to limits in their light concentration ability. Plasmonic devices offer a complimentary set of application opportunities enabled by large optical bandwidth and extreme miniaturization. While efficient stationary plasmonic metasurfaces have been realized,  and progress is being made in plasmo-mechanical systems, [9-12] a scalable and flexible approach for making devices near the physical limits of optical confinement and plasmo-mechanical coupling is currently lacking. Here, we introduce such a plasmo-mechanical device architecture, in which localized gap plasmon resonators with precise, large-area nanoscale gaps are embedded into arrays of moving silicon nitride nanostructures. Record optomechanical coupling of ≈ 2 THz∙nm-1 enables mechanical motion measurement from a 165nm × 350 nm device area with a 6 fm∙Hz-1/2 noise floor, 1.5 orders of magnitude lower than previously possible. Fabrication yields thousands of devices per chip with individually tailorable plasmonic and mechanical designs, and is compatible with optical lithography batch-fab
and Aksyuk, V.
Nanomechanical motion transduction with a scalable localized gap plasmon architecture, Nature Communications, [online], https://doi.org/10.1038/ncomms13746, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920417
(Accessed June 6, 2023)