Tun Cao

Tun Cao
Dalian University of Technology | DUT · School of opto-electronics engineering and instrumentation

About

139
Publications
21,100
Reads
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2,573
Citations
Citations since 2017
81 Research Items
2223 Citations
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Introduction
Tun Cao currently works at the School of opto-electronics engineering and instrumentation, Dalian University of Technology. Tun does research in Optical Engineering. Their most recent publication is 'Reconfigurable, graphene-coated, chalcogenide nanowires with a sub-10-nm enantioselective sorting capability'.

Publications

Publications (139)
Article
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Miniaturized nonvolatile reconfigurable optical components with a subwavelength thickness, extremely compact size, high-speed response, and low power consumption will be the core of next-generation all-optical integrated devices and photonic computing to replace traditional bulky optical devices and integrated circuits, which are reaching physical...
Article
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Surface lattice resonances (SLRs) with high-quality factors supported by metal nanoparticle arrays are useful for plasmonic nanolasers, biochemical sensors, and surface-enhanced Raman spectroscopy. Most nanoparticle arrays are fabricated on a substrate, and the refractive index mismatch between the substrate and superstrate suppresses the performan...
Article
Chirality induction, transfer, and manipulation have aroused great interest in achiral nanomaterials. Here, we demonstrate strong upconverted circularly polarized luminescence from achiral core-shell upconversion nanoparticles (UCNPs) via a plasmonic chiral metasurface-induced optical chirality transfer. The Yb3+-sensitized core-shell UCNPs with go...
Article
Metasurface optical holography represents an important technique for developing ultrathin diffractive optical elements. Among various designs, the metasurface devices with strong chiroptical responses offer a new degree of freedom to manipulate light fields. However, in a linear optical regime, it is usually complicated to realize strong chiroptica...
Article
Metasurfaces A self‐aligned suspended chiral bilayer metasurface via single‐step electron‐beam lithography is reported by Tun Cao, Yan Jun Liu, and co‐workers in article number 2203956. A huge optical chirality of 221° μm−1 is achieved by the free‐standing metasurfaces with overall thickness of 100 nm. The bilayer metasurface demonstrates label‐fre...
Article
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Zero-refractive-index (ZRI) phononic crystals (PhCs), in which acoustic waves can be transmitted without phase variations, have considerable potential for engineering wavefronts and thus are applicable to invisibility cloaking. However, the creation of the transmissive cloaking achieved by ZRI-PhCs is challenging under an oblique incidence, which s...
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Actively controlling the polarization states of terahertz (THz) waves is essential for polarization-sensitive spectroscopy, which has various applications in anisotropy imaging, noncontact Hall measurement, and vibrational circular dichroism. In the THz regime, the lack of a polarization modulator hinders the development of this spectroscopy. We th...
Article
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Chiral metasurfaces can exhibit a strong circular dichroism, but it is limited by the complicated fabrication procedure and alignment errors. Here, we demonstrate a new type of self‐aligned suspended chiral bilayer metasurface with only one‐step electron beam lithography exposure. A significant optical chirality of 221°/μm can be realized using sus...
Article
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Fast and efficient information processing and encryption, including writing, reading, and encryption memory, is essential for upcoming terahertz (THz) communications and information encryption. Here, we demonstrate a THz multi-level, nonvolatile, optically rewritable memory and encryption memory based on chalcogenide phase-change materials, Ge2Sb2T...
Article
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Optical tweezers are considered as a revolution, allowing for manipulating particles ranging in scale from a few hundred nanometers (nm) to several micrometers (μm). Near‐field optical force allows effective trapping of a broad range of entities, from atom to living cells. Yet, there are formidable challengings for existing on‐chip photonic trappin...
Article
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2D black phosphorus (BP) possesses an in‐plane anisotropy, offering another degree of freedom to create new optoelectronic and photonic devices, such as waveplates with atomic thickness. Yet, due to its very low energy bandgap, the anisotropy of BP crystal is mainly studied in the near‐infrared region and remains elusive in the visible region. Furt...
Article
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Metasurfaces, especially tunable ones, have played a major role in controlling the amplitude, phase, and polarization of electromagnetic waves and attracted growing interest, with a view toward a new generation of miniaturized devices. However, to date, most existing reconfigurable devices are bounded in volatile nature with sustained external ener...
Article
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The nonlinear optical properties of silicon have great potentials for developing all-optical switches and modulators, etc. Strategies based on all dielectric silicon photonic crystals and resonators have been proposed to design the nanophotonic devices with high nonlinearity. Nevertheless, the lack of compatible configuration with the mature CMOS t...
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Integrating tunable characteristics and multiple functions into a single metasurface attracts more and more attention. Herein, a reconfigurable bifunctional metasurface is proposed to realize the switch between broadband polarization conversion and absorption. The switchable performance can be achieved by changing the conductivity of phase‐change m...
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An all-dielectric metasurface with quasi-bound state in continuum was developed to enhance the optical force for chiral sorting.
Article
Up-to-date particle sieving schemes face formidable challenges for sieving label-free submicron molecules with similar sizes and dielectric constants but diverse shapes. Herein, optical sorting of polystyrene particles with various shapes is illustrated in optofluidic nanophotonic paired waveguide (ONPW) composed of chalcogenide semiconductor Sb2Se...
Article
Metasurface analog of electromagnetically induced transparency (EIT) provides a compact platform for generating a narrow‐band transmission window with very sharp spectral features. They hold promise for many appealing applications including ultrasensitive detectors, slow‐light devices, nonlinear optical devices etc. In particular, reconfigurable EI...
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Enantioseparation is crucial in pharmaceutics and agrochemicals. Compared to the current chemical technique, the optical enantioseparation is more effective means yet hampered by the weak chiral optical force. Recently, plasmonic nanostructures have been theoretically demonstrated to excite superchiral fields that can enhance enantioselective optic...
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Efficient thermal radiation in the mid-infrared (M-IR) region is of supreme importance for many applications including thermal imaging and sensing, thermal infrared light sources, infrared spectroscopy, emissivity coatings, and camouflage. The capability of controlling light makes metasurface an attractive platform for infrared applications. Recent...
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The third-order nonlinear processes in nanophotonic devices may have great potentials for developing ultra-compact nonlinear optical sources, ultrafast optical switches and modulators, etc. It is known that the performance of the nonlinear nanophotonic devices strongly relies on the optical resonances and the selection of appropriate nonlinear mate...
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Perfect absorption ranging from visible, infrared, terahertz, to microwave is desirable for solar cell, photodetection, telecommunications, and molecular sensing. Recently, the air/dielectric–metal stacks/substrate‐based asymmetric Fabry–Pérot (FP) cavity has attracted much attention owing to lithography‐free design which is scalable and low cost....
Article
The Greta oto butterfly has transparent wings with extraordinary omnidirectional anti-reflection behavior, owing to unusual nanostructures with random height and pitch/space distribution on its wing surface. The beauty and efficacy of such nanostructures are proven designs but difficult to reproduce en masse. Here, we establish a low-cost bottom-up...
Article
Next-generation color display entails miniaturization, reconfigurablity, flexibility, integration, and excellent workability. Recently, emerging 2D van der Waals materials offer a new opportunity to satisfy these requirements and attract intense attention, owing to their intrinsic in-plane anisotropy for polarization dependent photosensitivity, str...
Article
Nowadays, the electromagnetic properties of artificial photonic materials can be well-tuned via designs over their composition and geometries. However, engineering the properties of artificial materials at the nanoscale is challenging and costly. Here we demonstrate a facile and low-cost method for fabricating large-area silver nanoparticle metasur...
Article
Responsive photonic crystals (PCs), which can adjust structural colors in response to external stimuli, show great potential applications in displays, sensors, wearable electronics, encryption, and anticounterfeiting. In contrast, conventional structure-intrusive adjustment manners that external stimuli directly interact with the ordered arrays may...
Article
Two-dimensional (2D) materials attract wide attention due to their unique exciting physical properties, which offer new opportunities to design novel devices with enhanced or multiple functionalities. In particular, α -phase molybdenum trioxide ( α -MoO 3 ) is an emerging 2D material and exhibits strong anisotropic optical properties and low optica...
Article
Hyperbolic metamaterials (HMMs) attract increasing attentions due to their unique optical properties and offer new approaches for realizing novel functionalities in emerging photonic meta-devices. Tunable is one of the most attractive optical properties since multifunction optical devices are one of the important research directions. So far, most a...
Article
Experimental demonstration of light propagation with ultralow group velocity, i.e., slow light, allows for revolutionary solutions for time-domain processing and buffering of optical signals. It can spatially compress optical energy, which lessens the device footprint and enhances linear and nonlinear optical effects. Photonic crystal waveguides (P...
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Recently, metasurfaces based on phase-change materials (PCMs) have attracted increasing attention due to the dramatic optical properties contrast between amorphous and crystalline states. The chalcogenide PCMs can be reversibly switched by electrical or optical pulses, offering tunability and reconfigurability for the metasurfaces. In this Perspect...
Article
The ultrafast, reversible, nonvolatile and multistimuli responsive phase change of Ge-Sb-Te (GST) alloy makes it an interesting "smart" material. The optical features of GST undergo significant variation when its state changes between amorphous and crystalline, meaning that they are useful for tuning photonic components. A GST phase change material...
Article
Transformation optics (TO) has been recognized as an established scheme that can precisely manipulate electromagnetic surface wave propagations. Utilising the advantages of the TO technique, we proposed a TO device which can control the propagation direction of surface waves. The device is based on a generalized Eaton lens and can be realized on cu...
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In linear optics, metasurface represents an ideal platform for encoding optical information due to its unprecedented abilities of manipulating the intensity, polarization and phase of light wave with subwavelength meta-atoms. However, controlling various degrees of freedom of light in nonlinear optics remains elusive. Here we propose a nonlinear pl...
Article
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Anisotropic two‐dimensional (2D) materials with unique thermoelectric, electrical, and optical characteristics offer prospects for various angle‐dependent devices. Yet, few anisotropic 2D materials are exploited. Black phosphorus (BP) is a newly rediscovered 2D material with striking in‐plane anisotropy. However, experimental illustrations of the o...
Article
Strong mode coupling and Fano resonances arisen from exceptional interaction between resonant modes in single nanostructures have raised much attention for their advantages in nonlinear optics, sensing, etc. Individual electromagnetic multipole modes such as quadrupoles, octupoles, and their counterparts from mode coupling (toroidal dipole and nonr...
Article
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Efficient manipulation of nanoparticles and single molecules has always been of great interest and potential in nanotechnology. However, many challenges still remain in effectively functionalizing structures for this purpose. In this work, taking advantage of graphene's Dirac plasmon for its extreme confinement and tunability, a monolayer conveyor...
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Metamaterials analogue of electromagnetically induced reflectance (EIR) has attracted intense attentions since they can provide various applications for novel photonic devices such as optical detectors with a high sensitivity and slow-light devices with a low loss. The development of dynamic photonic devices desires a tunable EIR feature in metamat...
Preprint
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In the last decade phase change materials (PCM) research has switched from practical application in optical data storage toward electrical phase change random access memory technologies (PCRAM). As these devices are commercialised, we expect the research direction to switch once again toward electrical-photonic devices. The objective of this review...
Article
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Droplet microfluidics involving non-Newtonian fluids is of great importance in both fundamental mechanisms and practical applications. In the present study, breakup dynamics in droplet generation of semi-dilute polymer solutions in a microfluidic flow-focusing device were experimentally investigated. We found that the filament thinning experiences...
Article
2D van der Waals materials have attracted increasing attention in recent years due to their exciting physical properties and offer new opportunities for creating devices with enhanced or novel functionalities. In particular, α‐MoO3 is an emerging member of the fast‐growing 2D family with strong natural anisotropic optical properties. However, aniso...
Article
A cluster of gold nanoparticles (Au NPs) is dispersed on chalcogenide film to reduce the phase transition power of the chalcogenide layer, as shown by Tun Cao and co‐workers in article number 1901570. This reduced power is owing to the enhanced light absorptance through the strongly localized surface plasmon resonance of the Au NPs. Such a design i...
Article
Chalcogenide materials are attractive for all‐photonic phase‐change memories owing to their large optical contrast between amorphous and crystalline structural phases. However, high‐power heating pulses are required to switch these structural phases, which can limit the cyclability. To reduce power, Au nanoparticles (NPs) are embedded in a typical...
Article
Many previously observed strong chiroptical effects are limited to chiral metamaterials with complex three-dimensional building blocks. Recently, chiral metamirrors consisting of planar elements are proposed to selectively reflect one particular circularly polarized light (CPL) while absorbing the other, with the reflected one either preserving or...
Article
The objective of this paper is to understand the origin of the unusually large optical gap in amorphous chalcogenide phase change materials. The optical contrast between the crystalline and amorphous forms of phase‐change materials (PCM) is so marked as to make it ideal for data storage. Various explanations for this gap have been given, including,...
Article
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Transparent conductors for the next generation of soft electronic devices need to be highly stretchable, conductive, and transparent, while an inevitable challenge lies in enhancing them simultaneously. Cost‐effective silver nanowires (AgNWs) are widely used but the conventional random network yields a high junction resistance as well as degraded c...
Article
Recently, tunable high absorptance from various nanophotonics structures has been demonstrated. However most of these structures require nano-lithography, which is expensive and slow. Lithography-free tuneable absorbers are rarely explored for tuneable visible and near infrared photonics. Herein, we demonstrate a gold (Au)/chalcogenide dual-layer t...
Article
Chalcogenide phase‐change materials (CPCMs) possess a radically changeable optical property as switching the state between amorphous and crystalline. This makes CPCMs attractive for reconfigurable photonic devices. In article number 1900094 by Tun Cao and Mengjia Cen, the fundamentals in chalcogenide‐tuned photonics is introduced. Recent developmen...
Article
Recently, chalcogenide phase‐change materials (PCMs) photonics have become an emerging research field because the optical properties of the PCMs undergo a dramatic change during the amorphous–crystalline phase transition. The chalcogenide PCMs can be efficiently switched by electrical or short optical pulses, offering versatility in photonic applic...
Article
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Sweat collection and real time monitoring of sweat rate play essential roles in physiology monitoring and assessment of an athlete’s performance during exercise. In this paper, we report a micropump for sweat simulant collection based on the capillary–evaporation effect. An electrochemical sensor is integrated into the micropump, which monitors the...
Article
Third‐order harmonic generation (THG) plays a vital role in microscopy, optical communications, etc. Conventional methods of obtaining efficient THG in macroscopic crystals is already mature; however, they will finally limit the miniaturization and integration of on‐chip laser sources. To date, THG from either photonic crystals or metamaterials pro...
Article
Full-text available
The biomechanical properties of single cells show great potential for early disease diagnosis and effective treatments. In this study, a microfluidic device was developed for quantifying the mechanical properties of a single cell. Micropipette aspiration was integrated into a microfluidic device that mimics a classical Wheatstone bridge circuit. Th...
Preprint
Third-order harmonic generation (THG) plays a vital role in microscopy, optical communications etc. Conventional methods of obtaining efficient THG in macroscopic crystal is already mature; however, they will finally limit the miniaturization and integration of on-chip laser sources. To date, THG from either photonic crystals or metamaterials provi...
Article
Perfect absorbers that can efficiently absorb electromagnetic wave over a broad spectral range are crucial for energy harvesting, light detection, and optical camouflage. Recently, perfect absorbers based on the metasurface have attracted intensive attention. However, high performance metasurface absorbers in the visible spectrum require strict fab...
Article
Separating enantiomers is vital in chemical syntheses, life sciences, and physics. However, the usual chemical processes are inefficient. Recently, plasmonic nanostructures have drawn considerable attention for manipulating nanoparticles; however, only a few approaches are proposed to discriminate between entities that differ in terms of their hand...
Article
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Chiral surface plasmon polaritons (SPPs) produced by plasmonic nanowires can be used to enhance molecular spectroscopy for biosensing applications. Nevertheless, the switchable stereoselectivity and detection of various analytes are limited by a lack of switchable, chiral SPPs. Using both finite-element method simulations and analytic calculations,...
Article
In this paper, we undertook a three-dimensional flow field simulation of the steady flows through diffusers and nozzles with straight or serrated-sided walls to analyze the effect of channel structure on flow characteristics. The pressure and velocity profiles in the diffusers and nozzles as well as the net volumetric flow rate were obtained. Our s...
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We demonstrate a facile method to fabricate Ag-Sb2S3 nanoporous plasmonic absorbers on plastic, crystalline, and glassy substrates. Our lithography-free method exploits the immiscibility of Ag and Sb2S3 to control the surface morphology of the absorbing structure. We experimentally and theoretically show that the nanoporous structure exhibits a hig...
Article
Vanadium oxide (VO2) as a phase changing material possesses abrupt infrared (IR) transmission and thermal emissivity changing during the metal–insulator transition across transition temperature (τc) of 68 °C. However, the high τc, moderate IR transmission and emissivity regulating ability limits its applications in various fields. A VO2/carbon hybr...
Article
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A controlled quantitative loading of dynamic biochemical signals on cells in vitro is essential for cell dynamic analysis. Microfluidics provides the potential for reproducing and controlling spatio-temporal biochemical signals through the various microfluidic channels. Herein we investigate the transmission characteristics of dynamic biochemical s...
Article
Transformation optics (TO) technique, which establishes the equivalence between a curved space to a spatial distribution of inhomogeneous constitutive parameters, has enabled an extraordinary paradigm on manipulating wave propagation. However, extreme constitutive parameters as well as a static nature of it inherently limit simultaneous achievement...
Article
Noble metals, like Ag and Au, are the most intensively studied plasmonic materials in the visible range. Plasmons in semiconductors, however, are usually believed to be in the infrared wavelength region due to the intrinsic low carrier concentrations. Herein, we observe the edge plasmon modes of Bi2Te3, a narrow-band gap semiconductor, in the visib...
Article
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We achieve long-range and continuous optical pulling in a periodic photonic crystal background, which supports a unique Bloch mode with the self-collimation effect. Most interestingly, the pulling force reported here is mainly contributed by the intensity gradient force originating from the self-induced backaction of the object to the self-collimat...
Article
Plasmonic nanowire was found to generate chiral surface plasmon polaritons (SPPs), with the perspective of enhancing molecular spectroscopy for biosensing applications. However, the lack of chiroptical switches exhibits significant limitations in detecting a multitude of various analytes with a high sensitivity and in asymmetric catalysis to provid...
Article
We numerically show that a giant lateral optical force (LOF) acting on sub-10 nm non-chiral particles can be obtained using a dipole-quadrupole (DQ) Fano resonance (FR). This DQ-FR is excited by an asymmetric plasmonic bowtie nanoantenna array (BNA), which is based on a Au/Ge2Sb2Te5/Au trilayer. The LOF behaves in a direction in which the incident...