Jun-Yu Ou

Jun-Yu Ou
University of Southampton · Optoelectronics Research Centre (ORC)

PhD

About

225
Publications
16,491
Reads
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2,654
Citations
Additional affiliations
January 2016 - present
University of Southampton
Position
  • Senior Researcher
October 2014 - December 2015
University of Southampton
Position
  • PostDoc Position
July 2014 - September 2014
University of Southampton
Position
  • Senior Research Assistant
Education
January 2010 - September 2014
University of Southampton
Field of study
  • Optoelectronics
September 2002 - June 2005
September 1998 - June 2002
National Chung Hsing University
Field of study
  • Physics

Publications

Publications (225)
Article
We introduce mechanically reconfigurable photonic metamaterials (RPMs) as a flexible platform for realizing metamaterial devices with reversible and large-range tunable characteristics in the optical part of the spectrum. Here we illustrate this concept for a temperature-driven RPM exhibiting reversible relative transmission changes of up to 50%.
Article
Full-text available
Current efforts in metamaterials research focus on attaining dynamic functionalities such as tunability, switching and modulation of electromagnetic waves. To this end, various approaches have emerged, including embedded varactors, phase-change media, the use of liquid crystals, electrical modulation with graphene and superconductors, and carrier i...
Article
Full-text available
The development of metamaterials, data processing circuits and sensors for the visible and ultraviolet parts of the spectrum is hampered by the lack of low-loss media supporting plasmonic excitations. This has driven the intense search for plasmonic materials beyond noble metals. Here we show that the semiconductor Bi1.5Sb0.5Te1.8Se1.2, also known...
Article
Metamaterial nanostructures actuated by light give rise to a large optical nonlinearity. Plasmonic metamolecules on a flexible support structure cut from a dielectric membrane of nanoscale thickness are rearranged by optical illumination. This changes the optical properties of the strongly coupled plasmonic structure and therefore results in modula...
Preprint
Full-text available
Time 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...
Article
Flexural oscillations of freestanding films, nanomembranes, and nanowires are attracting growing attention for their importance to the fundamental physical and optical properties and device applications of two-dimensional and nanostructured (meta)materials. Here, we report on the observation of short–time scale ballistic motion in the flexural mode...
Article
Stimulated Brillouin scattering (SBS) has been widely applied in narrow line-width laser, microwave filters, optical gyroscopes and other fields. However, most research is limited within near-infrared to mid-infrared range. This is due to the limited transparent window in most materials, such as silicon and germanium. Aluminium Nitride (AlN) is a n...
Article
The tunable angle-selective transparency of hyperbolic metamaterials consisting of various multilayers of Dirac semimetal and dielectric materials are theoretically and numerically studied in the terahertz range. Three stack configurations are considered: alternating, sandwiched, and disordered. It is found that the proposed structures exhibit stro...
Conference Paper
This paper reports a novel attempt to build a model of nonlinear resonance behavior of very-high-frequency silicon nanoelectromechanical (NEM) resonators observed via 1-omega mixing resonance measurements. Time-dependent gate-beam voltage on the mixing measurement condition has been incorporated with the Duffing oscillator equation which is solved...
Article
Full-text available
Perfectly matched layer has been used for solving anchor‐loss limited quality factor in the Micro electromechanical systems. However, setting up a well‐behaved perfectly matched layer requires users to change the parameters of a perfectly matched layer to give correct results, while the current existing methods for choosing the right parameters are...
Conference Paper
The first realization of sub-Brownian motion metrology is reported. The position of a nanowire is measured with resolution better than 100 picometers via deep learning analysis of topologically structured light scattering on the nanowire
Conference Paper
Optically bistable light scattering is observed on oscillating nanowires decorated with plasmonic patterns. Coupling between plasmonic and highly nonlinear mechanical subsystems of the nanostructure facilitates bistability at only a few μW of incident optical power.
Conference Paper
We demonstrate that fluctuations in the optical properties of nanomechanical photonic metamaterials can reach 1% at room temperature. Such fluctuations arise from ‘Brownian’ motion and peak at the frequencies of the nanostructures’ natural mechanical modes.
Preprint
Full-text available
Despite recent tremendous progress in optical imaging and metrology, the resolution gap between atomic scale transmission electron microscopy and optical techniques has not been closed. Is optical imaging and metrology of nanostructures exhibiting Brownian motion possible with resolution beyond thermal fluctuations? Here we report on an experiment...
Preprint
Full-text available
Flexural oscillations of free-standing films, nano-membranes and nano-wires are attracting growing attention for their importance to the thermal, electrical and mechanical properties of 2D materials. Here we report on the observation of short-timescale ballistic motion in the flexural mode of a nano-membrane cantilever, driven by thermal fluctuatio...
Conference Paper
The resolution of conventional microscopy is limited to a half of the wavelength of light. We report on recent advances in applications of deep learning and topologically structured light to far-field nondestructive imaging with deep subwavelength resolution and to picometric metrology.
Conference Paper
A profound optical bistability in light scattering is observed in a pair of oscillating nanowires decorated with plasmonic patterns. The response becomes bistable at only a few μW of incident optical power, which is facilitated by coupling between the plasmonic and the highly nonlinear mechanical subsystems of the nanostructure.
Conference Paper
Scattering by a subwavelength particle in a structured light field containing phase singularities is highly sensitive to the particle’s position. Artificial intelligence-enabled analysis of superoscillatory light field scattering, at a wavelength of 490 nm, provides for experimental determination of the 3D position of 100 nm polystyrene spheres wit...
Conference Paper
We experimentally observe that fluctuations in metamaterial optical properties peak at the frequencies of the nanostructures’ natural mechanical modes, due to ‘Brownian’ motion. Fluctuations in flexural phonon density are the underlying mechanism for this motion, which is observed as fluctuations in optical properties reaching 1% at room temperatur...
Conference Paper
The relative positions of nanostructures can be measured with picometric resolution using scattering of free electrons or topologically structured light at sharp edges of the structures. Through artificial intelligence enabled analysis of scattered coherent light, sub-atomic resolution is achievable in single-shot measurements.
Article
We demonstrate a non-contact optical magnetic field sensor that is based on actuation of a metamaterial-microcavity by the magnetic Lorentz force. Magnetic field is transduced to a change of the sensor’s reflectivity. The microscale proof-of-concept metamaterial magnetometer can be read from a distance and offers 60 micrometer spatial, about 10 mic...
Article
Bolometers are detectors of electromagnetic radiation that usually convert the radiation-induced change of temperature of the detector into electric signals. Temperature-dependent electrical resistance in semiconductors and superconductors, the thermoelectric effect in thermocouples and the pyroelectric effect of transient electric polarization of...
Preprint
Full-text available
Optical devices with metastable states controlled with light (optical flip-flops) are needed in data storage, signal processing and displays. Although non-volatile optical memory relying on structural phase transitions in chalcogenide glasses has been widely used for optical data storage, beyond that, weak optical nonlinearities have hindered the d...
Article
Bolometers are detectors of electromagnetic radiation that usually convert the radiation-induced change of temperature of the detector into electric signals. Temperature-dependent electrical resistance in semiconductors and superconductors, the thermoelectric effect in thermocouples and the pyroelectric effect of transient electric polarization of...
Article
The combination of optical and mechanical resonances offers strong hybrid nonlinearities, bistability and the ability to efficiently control the optical response of nanomechanical photonic metamaterials with electric and magnetic field. While optical resonances can be characterized in routine transmission and reflection experiments, mapping the hig...
Article
In article number 2100803, Tiago Martins, Yihao Cui, Behrad Gholipour and co-workers demonstrate a fiber tip-integrated optical switch based on phase change metasurfaces capable of in-fiber and non-volatile optically-induced intensity and phase switching operation across the entire telecom frequency band.
Article
Demonstration of a fiber-integrated non-volatile reconfigurable metasurface providing high-contrast group delay dispersion switching functionality is reported, which may be engineered to operate at wavelengths across the near-infrared (telecoms) band. Light-induced amorphous-crystalline phase switching in a chalcogenide (germanium antimony tellurid...
Conference Paper
The optical properties of materials are determined by the spatial arrangement of their building blocks and nanomechanical metamaterials can be actuated by temperature changes, electric and magnetic fields, light and ultrasound. This provides an opportunity for sensing and light modulation based on engineered giant thermo-optical, electro-optical, m...
Article
We demonstrate experimentally that the distribution of the decay rates of nitrogen-vacancy centers in diamond becomes narrower by over five times for nanodiamonds embedded in thin chalcogenide films.
Article
We demonstrate experimentally two-fold enhancement of the decay rate of NV0 centers on diamond/Si substrate as opposed to a bare Si substrate. We link the decay enhancement to the interplay between the excitation of substrate modes and the presence of non-radiative decay channels. We show that the radiative decay rate can vary by up to 90% dependin...
Conference Paper
A nanowire array decorated with plasmonic resonators acts as optically bistable device. The optical properties of this metamaterial exhibit hysteresis and bistability when it is driven by a piezo actuator across its mechanical resonance frequency.
Conference Paper
We demonstrate an optical magnetic field sensor based on a metamaterial-microcavity. Actuation of the microcavity by the magnetic Lorentz force controls its reflectivity. Such sensors promise microscale spatial, sub-millisecond temporal and microtesla magnetic field resolution.
Article
Plasmonic tapered grooves have been proven to be good candidates for the excitation of gap surface plasmons (GSPs), surface plasmons trapped vertically inside a metallic tapered groove or slit. GSPs have attracted tremendous interest due to their unique properties of concentrating light in nanosized gaps with significant field enhancement, thus off...
Conference Paper
A nanowire array decorated with plasmonic resonators acts as optically bistable device. The optical properties of this metamaterial exhibit hysteresis and bistability when it is driven by a piezo actuator across its mechanical resonance frequency.
Conference Paper
Highly nonlinear behaviour observed in nano-electromechanical systems (NEMS) has been attracting much attention. In this study, a series of nonlinear hysteric resonance behaviours with respect to actuation voltage, observed in a doubly-clamped NEMS resonator, have been analysed by introducing a threshold determination equation into a model based on...
Conference Paper
We demonstrate an optical magnetic field sensor based on a metamaterial-microcavity. Actuation of the microcavity by the magnetic Lorentz force controls its reflectivity. Such sensors promise microscale spatial, millisecond temporal and microtesla magnetic field resolution.
Conference Paper
Electrogyration is electric-field-dependent polarization state rotation in chiral media. We demonstrate a metamaterial with a quadratic electrogyration constant of 7.8 × 10<sup>-14</sup> rad m<sup>2</sup> V<sup>-2</sup>, which is a million times stronger than in natural materials.
Conference Paper
Components of photonic nanostructures exhibit picometric thermal movements affectingtheir optical properties. We report the first observation of ballistic (non-Brownian) thermal motionof a microcantilever, at timescales shorter than those of the erratic Brownian regime.
Conference Paper
We demonstrate experimentally label-free far-field imaging of subwavelength objects at resolution greater than λ/20, exceeding the diffraction limit by an order of magnitude. Our imaging approach, termed Deeply Subwavelength Topological Microscopy (DSTM), is based on the combination of illumination with topological structured illumination and artif...
Preprint
Full-text available
We demonstrate experimentally that the distribution of the decay rates of nitrogen-vacancy centers in diamond becomes narrower by over five times for nanodiamonds embedded in thin chalcogenide films.
Article
THz molecular fingerprint sensing is a promising non-destructive method to accurately detect ultra-thin carbon-based materials in the nanoscale. Due to their extremely low THz absorption, plasmonic metamaterials or all-dielectric metasurfaces have been adopted to enhance the light-matter interaction for detection. However, they cause considerable p...
Preprint
We demonstrate experimentally two-fold enhancement of the decay rate of NV$^0$ centers on diamond/Si substrate as opposed to a bare Si substrate. We link the decay enhancement to the interplay between the excitation of substrate modes and the presence of non-radiative decay channels. We show that the radiative decay rate can vary by up to 90% depen...
Article
Full-text available
Nanoscale objects move fast and oscillate billions of times per second. Such movements occur naturally in the form of thermal (Brownian) motion while stimulated movements underpin the functionality of nano-mechanical sensors and active nano-(electro/opto)mechanical devices. Here we introduce a methodology for detecting such movements, based on the...
Conference Paper
A series of nonlinear resonance behaviors, observed for multiple systematically designed doubly-clamped NEMS resonators, have been successfully analyzed using a model which was developed based on the nonlinear Duffing equation and experimentally estimated parameter inputs. Key parameters in the model, such as resonance frequency, nonlinear cubic st...
Article
Full-text available
A non-intrusive far-field optical microscopy resolving structures at the nanometer scale would revolutionize biomedicine and technology but is not yet available. Here a new type of microscopy is introduced, which reveals the fine structure of an object through its far-field scattering pattern under illumination with light containing deeply subwavel...
Article
Full-text available
One of the most fascinating properties of chiral molecules is their ability to rotate the polarization of light. Since Faraday’s experiments in 1845 it has been known that non-reciprocal polarization rotatory power can be induced by a magnetic field. But can reciprocal polarization rotation in chiral molecules be influenced by an electric field? In...
Conference Paper
Wereview the exceptional variety of functionalities accessible by design in nanomechanical photonic metamaterials, whereindynamic reconfiguration of sub-wavelength structure by external stimuli can yield extreme and unusual electro-, magneto-, thermo-, acousto-and nonlinear optical response characteristics.
Conference Paper
The building blocks of nanomechanical photonic metamaterials are perturbedby collisions with atoms of ambient atmosphericgas 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 u...
Conference Paper
We introduce a non-intrusive far-field optical microscopy, which reveals the fine structure of anobject through its far-field scattering pattern under illumination with topologically structuredlight containing deeply subwavelength singularity features. The object is reconstructed by aneural network trained on a large number of scattering events. We...
Conference Paper
The nanomechanical metamaterials offer the possibilities of manipulating exotic electromagnetic properties on demand. Such metamaterial exhibit profound electro-optical, magneto-optical and acousto-optical switching and modulation, optical nonlinearity for modulating light with light, asymmetric transmission, and tunable chirality. The electromagn...
Preprint
We have developed a technique that extends static scanning electron microscopic imaging to include hyperspectral mapping of fast thermal and externally-driven movements at up to Megahertz frequencies. It is based on spectral analysis of the secondary electron flux generated by a focused electron beam incident on the moving object. We demonstrate de...
Conference Paper
We introduce a new far-field and label-free imaging paradigm based on combining singularity illumination with artificial-intelligence enabling reconstruction of an object from the scattered light. We demonstrate imaging resolution beyond X/100.
Conference Paper
Nitrogen vacancy (NV) centers in diamond exhibit long coherence lifetimes at room temperature, which renders them ideal candidates for quantum information and sensing applications. The emission characteristics of NV centers demonstrate high sensitivity to a range of stimuli including electric and magnetic fields, dielectric environment, strain, tem...
Article
We report the experimental demonstration of deeply subwavelength far-field optical microscopy of unlabeled samples. We beat the ∼λ/2 diffraction limit of conventional optical microscopy several times over by recording the intensity pattern of coherent light scattered from the object into the far-field. We retrieve information about the object with...
Article
Full-text available
Plasmonic metamaterials have wide applications on light trapping and manipulation. However, most of their design typically rely on solving Maxwell’s equations via computational electromagnetics, which is time-consuming and limits the design flexibility. Here, we combine the transmission line circuit theory to design the plasmonic stack metamaterial...