1,721,022 research outputs found
Dataset to support the Southampton Doctoral thesis 'Atomic Scale Dynamics of Thermal and Driven Motion in Photonic Nanostructures'
No full textThis dataset supports the Doctoral Thesis by Tongjun Liu (2023)
Atomic Scale Dynamics of Thermal and Driven Motion in Photonic Nanostructures.
AWARDED BY: University of Southampton
DATE OF AWARD: 2023
The dataset consists of 4 sub-folders containing data presented in Chapters 3, 4, 5 and 6 of the Thesis, respectively.
Each sub-folder contains separate folders with data for each figure in the Thesis. Data files are labelled with the figure number and panel they correspond to as well as a short description.
Data can be viewed using Excel plots, MATLAB plots
Related Funders:
Engineering and Physical Sciences Research Council (EPSRC)
Chinese Scholarship Council (CSC)
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Atomic scale dynamics of thermal and driven motion in photonic nanostructures
No full textThis 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.<p class="MsoNormal"/
Dataset for the journal article 'Photonic Metamaterial Analogue of a Continuous Time Crystal'
No full textExperimental data presented in the paper published in Nature Physics:
Photonic metamaterial analogue of a continuous time crystal, Tongjun Liu, Jun-Yu. Ou, Kevin F. MacDonald, Nikolay I. Zheludev, Nat. Phys.
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Hyperspectral visualization of picometric motion
No full textThe motion of nanostructures can be measured with picometric resolution using scattering of free electrons at sharp edges of the structures. Motion at the nano- to atomic scale is of growing technological importance and fundamental interest, in nano-electro-mechanical systems (NEMS), advanced materials (e.g. nanowires, 2D materials), mechanically reconfigurable photonic metamaterials; and in the study of systems governed by Van der Waals and Casimir forces, and quantum phenomena. However, there are no routinely available technologies for quantifying and spatially mapping fast, complex movements of picometric amplitude in nanostructures. We show how the spectrallyresolved detection of scattering from a tightly-focused free-electron beam incident on the sharp edges of a nano-object can provide for quantitative 3D visualization of motion at the picoscale. For a range of nano/microstructures, from simple cantilevers to photonic metamaterials and MEMS comb-drive actuators, we demonstrate measurements of thermal (cf. Brownian) motion amplitudes down to a noise-equivalent displacement level of 1 pm/Hz1/2, and the mapping of driven-motion oscillatory ‘mode shapes’ with spatial (SEM imaging) resolution far beyond the diffraction limit applicable to optical vibrometry techniques.We also report on the first observation of short-timescale ‘ballistic’ thermal motion in the flexural mode of a nanomembrane cantilever, driven by thermal fluctuation of flexural phonon numbers in the membrane: over intervals <10 μs, the membrane is found to move ballistically, at an average constant velocity of ~300 μm/s, while Brownian-like dynamics emerge for longer observation times. Access to the ballistic regime provides verification of the equipartition theorem and Maxwell-Boltzmann statistics for flexural modes and presents opportunities in fast thermometry and mass sensing
High-frequency nano-motion imaging of artificial nanostructures
No full textThere is growing interest and technological opportunity in nanomechanics and the fundamentals of nano- to pico-scale dynamics, which derive from the fact that electromagnetic and quantum forces become stronger as the dimensions of objects decrease, competing with elastic forces at sub-micron scales; while movements become faster as mass decreases, achieving Gigahertz bandwidth at the nanoscale.We report on a novel approach to the visualization of such movements that is based on the detection of secondary electrons and photons emerging from the interaction of a focused electron beam with moving components of nano-objects. The technique extends the static (zero-frequency) imaging capabilities of a conventional scanning electron microscope to enable hyperspectral spatial mapping of fast (MHz-GHz) thermal and externally-driven nano- to pico-scale motion in nanostructures
High-frequency nano-motion electron imaging for artificial nanostructures
No full textDevelopment of future nanomechanical devices and sensors demands characterisation of fast movements, typically of sub-nanometre amplitude at MHz-GHz frequencies. We report on a novel approach to the visualization of nanoscale movements that is based on the detection of secondary electrons and photons emerging from the interaction of a focused electron beam with moving components of nano-objects, which may be actuated thermally or by external forces
Ultrafast hyperspectral nanomotion imaging of ballistic and Brownian motion in metamaterial nanostructures
No full textThe building blocks of nanomechanical photonic metamaterials are perturbed by collisions with atoms of ambient atmospheric gas and by phonons in the crystal lattice of the constituent materials. Between collisions movements are ballistic, becoming diffusive (Brownian) at longer time scales. We show how one may distinguish between these regimes using ultrafast hyperspectral SEM nanomotion imaging and discuss their manifestation in the time-dependent optical properties of the metasurfaces
Metamaterial analogue of continuous time-crystal
No full textTime crystals are an eagerly sought phase of matter in which time-translation symmetry is broken. Quantum time crystals with discretely broken time-translation symmetry have been demonstrated in trapped atomic ions, atoms and spins while continuously broken time-translation symmetry has been observed in an atomic condensate inside an optical cavity. Here we report that a classical metamaterial nanostructure, a twodimensional array of plasmonic metamolecules supported on flexible nanowires, can be driven to a state possessing all key features of a continuous time crystal: continuous coherent illumination by light resonant with the metamolecules’ plasmonic modes triggers a spontaneous phase transition to a state in which transmissivity oscillations result from a many-body interaction among plasmonic metamolecules and which is characterized by long range order in space and time. As the state can be manipulated optically, the phenomenon is of interest to topological and non-Hermitian physics and application in frequency conversion, memory, modulation, nonreciprocity and amplification
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