Atomic scale dynamics of thermal and driven motion in photonic nanostructures

Abstract

This Thesis reports on the study of atomic scale dynamics of thermal and driven motion in nanomechanical and nano-optomechanical photonic metamaterials system including their atomic scale movement visualization and control. I have developed a sub-atomic motion visualization technique combining picometric displacement sensitivity with the nanometric spatial resolution of a conventional scanning electron microscope, and demonstrated its application in characterization of thermomechanical (Brownian) motion in nanomechanical structures, nanomechanical photonic metamaterials, NEMS/MEMS devices and biological structures. Using this technique, I have reported on the first observation of short-timescale ballistic motion in the flexural mode of a nano-membrane cantilever, driven by thermal fluctuations of flexural phonons. Within intervals <10 µs, the membrane moves ballistically at a constant velocity of ~300 µm/s, on average. Access to ballistic regime provides the first experimental verification of the equipartition theorem and Maxwell-Boltzmann statistics for flexural modes. For the first time I have optically resolved the average position of a nanowire with an absolute error of ~30 pm using light at a wavelength of λ= 488 nm, thus providing the first example of sub-Brownian metrology with λ/10,000 resolution. To localize the nanowire, I employed a deep learning analysis of the scattering of topologically structured light, which is highly sensitive to the nanowire’s position. For the first-time, I have demonstrated: a) optical parametric control of the spectrum of thermomechanical motion on an array of nano-opto-mechanical resonators; b) phononic frequency comb generation by the array; c) thermal energy exchange between two coupled oscillators within an optically driven array. Collectively, these works advance the visualization and control of photonic nanostructures at the picometre scale, thus opening up the exciting field of picophotonics.

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Identifiers

ORCID for Kevin MacDonald: orcid.org/0000-0002-3877-2976

ORCID for Jun-Yu Ou: orcid.org/0000-0001-8028-6130

ORCID for Nikolai Zheludev: orcid.org/0000-0002-1013-6636

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