Zhaogang Dong

Zhaogang Dong
Institute of Materials Research and Engineering, Singapore · Nanofabrication

doctor of philosophy

About

87
Publications
16,100
Reads
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1,975
Citations
Introduction
Plasmonics; sub-10-nm fabrication; light-matter interactions at the nanoscale; nonlinear plasmonics; dielectric nanostructures
Additional affiliations
April 2018 - present
Institute of Materials Research and Engineering, Singapore
Position
  • Researcher
April 2016 - March 2018
Institute of Materials Research and Engineering, Singapore
Position
  • Researcher
October 2012 - March 2016
Institute of materials Research and engineering
Position
  • Scientist I
Description
  • Sub-10 nm nano-plasmonics structure fabrication using electron beam lithography

Publications

Publications (87)
Article
Full-text available
Bound-states-in-the-continuum (BIC) is an emerging concept in nanophotonics with potential impact in applications, such as hyperspectral imaging, mirror-less lasing, and nonlinear harmonic generation. As true BIC modes are non-radiative, they cannot be excited by using propagating light to investigate their optical characteristics. In this paper, f...
Article
Full-text available
Exciton is a bosonic quasiparticle consisting of a pair of electron and hole, with promising potentials for optoelectronic device applications, such as exciton transistors, photodetectors and light emitting devices. However, the charge-neutral nature of excitons renders them challenging to manipulate using electronics. Here we present the generatio...
Article
Metasurfaces, a two-dimensional (2D) form of metamaterials constituted by planar meta-atoms, exhibit exotic abilities to tailor electromagnetic (EM) waves freely. Over the past decade, tremendous efforts have been made to develop various active materials and incorporate them into functional devices for practical applications, pushing the research o...
Article
Full-text available
Two-dimensional (2D) semiconductors could potentially replace silicon in future electronic devices. However, the low carrier mobility in 2D semiconductors at room temperature, caused by strong phonon scattering, remains a critical challenge. Here we show that lattice distortions can reduce electron–phonon scattering in 2D materials and thus improve...
Article
Full-text available
Subwavelength dielectric resonators assembled into metasurfaces have become a versatile tool for miniaturizing optical components approaching the nanoscale1–3. An important class of metasurface functionalities is associated with asymmetry in both the generation and transmission of light with respect to reversals of the positions of emitters and rec...
Article
Coating materials serve the purposes to protect, enhance and/or confer additional functionalities and properties to the underlying object surface or bulk materials. In recent years, nanotechnologies have been extensively incorporated into the functional coatings as manipulation of materials at the nanoscale can impart some unique chemical, mechanic...
Article
The Institute of Materials Research and Engineering (IMRE) is a research institute of the Science and Engineering Research Council (SERC), Agency for Science, Technology and Research (A*STAR). IMRE was established in September 1997. Over the past 25 years, IMRE has developed core competencies and interdisciplinary teams for material development fro...
Preprint
Full-text available
In optical anti-counterfeiting, several distinct optically variable devices (OVDs) are often concurrently employed to compensate for the insufficient security level of constituent OVDs. Alternatively, metasurfaces that exhibit multiple optical responses effectively combine multiple OVDs into one, thus significantly enhancing their security and hind...
Preprint
Digital camera sensors utilize color filters on photodiodes to achieve color selectivity. As color filters and photosensitive silicon layers are separate elements, these sensors suffer from optical cross-talk, which sets limits to the minimum pixel size. In this paper, we report hybrid silicon-aluminum nanostructures in the extreme limit of zero di...
Article
Plexcitonic strong coupling has ushered in an era of room‐temperature quantum electrodynamics at the nanoscale. Realizing its potential applications from single‐molecule spectroscopy to room‐temperature quantum technologies on an industrial level requires scalable and mass‐producible plasmonic cavities that provide ease of access and control for qu...
Article
It remains a challenge to directly print arbitrary three-dimensional shapes that exhibit structural colors at the micrometer scale. Woodpile photonic crystals (WPCs) fabricated via two-photon lithography (TPL) are elementary building blocks to produce 3D geometries that generate structural colors due to their ability to exhibit either omnidirection...
Article
Full-text available
While structural colors are ubiquitous in nature, saturated reds are mysteriously absent. This long-standing problem of achieving Schrödinger's red demands sharp transitions from "stopband" to a high-reflectance "passband" with total suppression of higher-order resonances at blue/green wavelengths. Current approaches based on nanoantennas are insuf...
Preprint
It remains a challenge to directly print three-dimensional arbitrary shapes that exhibit structural colors at the micrometer scale. Woodpile photonic crystals (WPCs) fabricated via two-photon lithography (TPL) are promising as building blocks to produce 3D geometries that generate structural colors due to their ability to exhibit either omnidirecti...
Preprint
Full-text available
Metasurfaces, a two-dimensional (2D) form of metamaterials constituted by planar meta-atoms, exhibit exotic abilities to freely tailor electromagnetic (EM) waves. Over the past decade, tunable metasurfaces have come to the frontier in the field of nanophotonics, with tremendous effort focused on developing and integrating various active materials i...
Preprint
Full-text available
Plexcitonic strong coupling has ushered in an era of room-temperature quantum electrodynamics that is achievable at the nanoscale, with potential applications ranging from high-precision single-molecule spectroscopy to quantum technologies functional under ambient conditions. Realizing these applications on an industrial scale requires scalable and...
Article
There are various concerns with current sunscreen actives in the sun care industry which pushes for a natural-based active that is sustainable as well as effective. Lignin is a natural polymer, capable of ultraviolet (UV) filtration and maintaining photostability. In this study, a variety of tuneable lignin-poly(ethylene glycol) (LP) nanodiamond (L...
Article
Full-text available
Hybrid dielectric metasurfaces have emerged as a promising approach to enhancing near field confinement and thus high optical nonlinearity by utilizing low loss dielectric rather than relatively high loss metallic resonators. A wider range of applications can be realized if more design dimensions can be provided from material and fabrication perspe...
Article
Full-text available
Multistate Tuning In article number 2104627, Renshaw Wang, Qi Jie Wang, Hong Liu, and co-workers demonstrate multistate tuning of third-harmonic generation via hybrid nonlinear metasurfaces. The metasurfaces consisting of GST–silicon split ring resonators offer a large third-order nonlinearity in the visible range. A high Q-factor Fano resonance of...
Preprint
Full-text available
Subwavelength dielectric resonators assembled into metasurfaces have become versatile tools to miniaturise optical components towards the nanoscale. An important class of such functionalities is associated with asymmetries in both generation and propagation of light with respect to reversals of the positions of transmitters and receivers. A promisi...
Preprint
Dielectric optical nanoantennas play an important role in color displays, metasurface holograms, and wavefront shaping applications. They usually exploit Mie resonances as supported on nanostructures with high refractive index, such as Si and TiO2. However, these resonances normally cannot be tuned. Although phase change materials, such as the germ...
Preprint
While structural colors are ubiquitous in nature, saturated reds are mysteriously absent. Hence, a longstanding problem is in fabricating nanostructured surfaces that exhibit reflectance approaching the theoretical limit. This limit is termed the Schrodinger red and demands sharp spectral transitions from "stopband" to a high reflectance "passband"...
Preprint
Bound-states-in-the-continuum (BIC)is a wave-mechanical concept that generates resonances with vanishing spectral linewidths. It has many practical applications in Optics, such as narrow-band filters, mirror-less lasing, and nonlinear harmonic generation. As true BIC optical modes non-radiative and confined to the near field of nanostructures, they...
Preprint
Hybrid dielectric metasurfaces have emerged as a promising approach to enhancing near field confinement and thus achieving high optical nonlinearity using low loss dielectrics. Additional flexibility in design and fabrication of hybrid metasurfaces allows dynamic control of light, which is value-added for a wider range of applications. Here, we dem...
Article
Optical masquerades are a low-cost camouflage strategy that avoids the hidden objects to be recognized despite being detected. Here, we demonstrate an optical holography-based masquerade that could encode the camouflaged object ("bomb") into another uncorrelated phase object ("dog") by using transmissive dielectric metasurfaces with the total effic...
Article
Efficient generation of anti-Stokes emission within nanometric volumes enables the design of ultracompact, miniaturized photonic devices for a host of applications. Many subwavelength crystals, such as metal nanoparticles and two-dimensional layered semiconductors, have been coupled with plasmonic nanostructures for augmented anti-Stokes luminescen...
Conference Paper
We demonstrate a novel class of metadevices with asymmetric nonlinear response. We fabricate translucent metasurfaces that generate completely independent images in transmission for the opposite directions of illumination at the third-harmonic frequency.
Conference Paper
We experimentally demonstrate tunable amplitude of third harmonic generation in silicon metasurface in transmission mode using phase change material, Ge 2 Sb 2 Te 5 , layer of thickness 5 nm only.
Conference Paper
We design, fabricate, and demonstrate translucent metasurfaces that generate images in transmission at third-harmonic frequency. Such metasurfaces create different and completely independent images for the opposite directions of illumination.
Article
Full-text available
Structural colors traditionally refer to colors arising from the interaction of light with structures with periodicities on the order of the wavelength. Recently, the definition has been broadened to include colors arising from individual resonators that can be subwavelength in dimension, e.g., plasmonic and dielectric nanoantennas. For instance, d...
Article
Camouflage is critical for many living organisms to survive in the natural world and has stimulated the applications, such as optical cloaking and military affairs. However, most applications adopt crypsis-type camouflage that prevents the organisms from being detected by matching the environment, which is challenging to realize large angle-of-view...
Article
This work presents a procedure for large-area patterning of designed plasmon resonators that are much smaller than possible with conventional lithography techniques. Fused Colloidal Nanopatterning combines directed self-assembly and controlled fusing of spherical colloidal nanoparticles. The two-step approach first patterns a surface covered with h...
Article
Full-text available
Metasurfaces as artificially nanostructured interfaces hold significant potential for multi-functionality, which may play a pivotal role in the next-generation compact nano-devices. The majority of multi-tasked metasurfaces encode or encrypt multi-information either into the carefully tailored metasurfaces or in pre-set complex incident beam arrays...
Article
Although Si acts as an electrical semiconductor, it has properties of an optical dielectric. Here, we revisit the behavior of Si as a plasmonic metal. This behavior was previously shown to arise from strong interband transitions that lead to negative permittivity of Si across the ultra-violet spectral range. However, so far, few have studied the pl...
Article
Full-text available
The coloration of some butterflies, Pachyrhynchus weevils, and many chameleons are notable examples of natural organisms employing photonic crystals to produce colorful patterns. Despite advances in nanotechnology, we still lack the ability to print arbitrary colors and shapes in all three dimensions at this microscopic length scale. Here, we intro...
Article
The rings, spots and stripes found on some butterflies, Pachyrhynchus weevils, and many chameleons are notable examples of natural organisms employing photonic crystals to produce colorful patterns. Despite advances in nanotechnology, we still lack the ability to print arbitrary colors and shapes in all three dimensions at this microscopic length s...
Preprint
The rings, spots and stripes found on some butterflies, Pachyrhynchus weevils, and many chameleons are notable examples of natural organisms employing photonic crystals to produce colorful patterns. Despite advances in nanotechnology, we still lack the ability to print arbitrary colors and shapes in all three dimensions at this microscopic length s...
Article
Plasmonic antennas have been widely used to enhance the infrared absorption of molecular moieties, owing to their ability to localize mid-infrared light into nanometer spaces at desired wavelengths. However, at mid-infrared wavelengths, these metallic plasmonic antennas do not benefit from the wavelength-scaling that allows for the smaller sizes of...
Data
Wide-Gamut Plasmonic Color Palettes with Constant Subwavelength Resolution _ Supporting Information
Article
Artwork often needs to be verified for authenticity during transactions. Electronic tags and labels are easily spotted and hence counterfeited. A covert and effective tag needs to be: (1) microscopic, (2) camouflaged into the surroundings, and (3) contain multiple sets of information. Here, we developed aluminum (Al) nanostructures that resonate ac...
Article
Full-text available
Absract Considerable attention has been paid recently to coherent control of plasmon resonances in metadevices for potential applications in all-optical light-with-light signal modulation and image processing. Previous reports based on out-of-plane coherent control of plasmon resonances were established by modulating the position of a metadevice in...
Article
Full-text available
Nanostructured metasurfaces demonstrate extraordinary capabilities to control light at the subwavelength scale, emerging as key optical components to physical realization of multitasked devices. Progress in multitasked metasurfaces has been witnessed in making a single metasurface multitasked by mainly resorting to extra spatial freedom, for exampl...
Article
A hybrid metal-dielectric nanoantenna promises to harness the large Purcell factor of metallic nanostructures while taking advantage of the high scattering directivity and low dissipative losses of dielectric nanostructures. Here we investigate a compact hybrid metal-dielectric nanoantenna that is inspired by the Yagi-Uda design. It comprises a met...
Article
Monolayer two-dimensional transition metal dichalcogenides (2D TMDCs) exhibit promising characteristics in miniaturized nonlinear optical frequency converters, due to their inversion asymmetry and large second-order nonlinear susceptibility. However, these materials usually have a very short light interaction lengths with the pump laser because the...
Article
Localized optical resonances in metallic nanostructures have been increasingly used in color printing, demonstrating unprecedented resolution but limited in color gamut. Here, we introduce a new nanostructure design, which broadens the gamut while retaining print resolution. Instead of metals, silicon nanostructures that exhibit localized magnetic...
Article
We extend the fabrication method of Template Assisted Metal Dewetting (TeAMeD) to create near-infrared resonant nanostructures in an Au film without the need for etching or lift-off. TeAMeD has previously been used to generate high aspect-ratio sub-10 nm apertures, but struggles to generate larger apertures (>100 nm). In this work, we introduce a m...
Article
Directed self-assembly of nanoparticles using topographical templates has demonstrated great capabilities of ordering particles at their maximum packing fraction resulting from template confinement effects and free energy minimization. However, to self-assemble nanostructures at a lower packing fraction with a precise control over particle's positi...
Article
We report a comprehensive experimental study of the polarization dependence between excitation and photoluminescence (PL) emission from single dolmen-like metallic nanostructures that exhibit both Fano-like and Lorentz-like plasmon resonances. Though the PL spectra of this plasmonic "molecule" also exhibit the Fano and Lorentz signature, the emitte...
Article
Full-text available
Color printing with plasmonic resonators can overcome limitations in pigment-based printing approaches. While layering in pigment-based prints results in familiar color mixing effects, the color effects of stacking plasmonic resonator structures have not been investigated. Here, we demonstrate an experimental strategy to fabricate a 3-tiered comple...
Article
Directed self-assembly of nanoparticles (DSA-n) is an approach that creates suitable conditions to capture nanoparticles randomly dispersed in a liquid and position them into predefined locations on a solid template. Although DSA-n is emerging as a potential bottom-up patterning technique to build nanostructures using nanoparticles of various sizes...
Article
Graphene has emerged as a promising candidate for optoelectronic applications due to its broadband absorption and ultrafast carrier mobility. However, its prominent disadvantages, i.e., the zero bandgap and ultrafast carrier lifetime, limit its usage in optoelectronic applications. Although patterning graphene into nanoribbons is an effective strat...
Article
Full-text available
Impressive properties arise from the atomically thin nature of transition metal dichalcogenide two-dimensional materials. However, being atomically thin limits their optical absorption or emission. Hence, enhancing their photoluminescence by plasmonic nanostructures is critical for integrating these materials in optoelectronic and photonic devices....
Data
Supplementary Figures 1-8, Supplementary Notes 1-4 and Supplementary References.
Article
Localized surface plasmon resonance (LSPR) on metallic nanostructures is able to enhance photoluminescence (PL) emission significantly. However, the mechanism for anomalous blue-shifted peak of PL emission from metallic nanostructures, relative to the corresponding scattering spectra, is still unclear so far. In this paper, we presented the detaile...
Article
The dielectric metasurface hologram promises higher efficiencies due to lower absorption than its plasmonic counterpart. However, it has only been used, up to now, for controlling linear-polarization photons to form single-plane holographic images in the near-infrared region. Here, we report a transmission-type metahologram achieving images in thre...
Conference Paper
We demonstrated that depositing HfO2 film on graphene nanoribbons greatly enhance the mobility through weakening the Coulombic interactions. As a result, the graphene nanoribbon photodetectors with HfO2 layer exhibits high responsivity of ~0.4 A/W at room temperature
Article
Full-text available
Graphene has drawn tremendous attention as a promising candidate for electronic and optoelectronic applications owing to its extraordinary properties, such as broadband absorption and ultrahigh mobility. Nevertheless, the absence of a bandgap makes graphene unfavorable for digital electronic or photonic applications. Although patterning graphene in...