Showing papers by "Din Ping Tsai published in 2013"
TL;DR: Very narrow isolated symmetric Lorentzian transmission lines in toroidal metamaterials are demonstrated, which exploits the long sought non-trivial non-radiating charge-current excitation based on interfering electric and toroidal dipoles.
Abstract: Engaging strongly resonant interactions allows dramatic enhancement of functionalities of many electromagnetic devices. However, resonances can be dampened by Joule and radiation losses. While in many cases Joule losses may be minimized by the choice of constituting materials, controlling radiation losses is often a bigger problem. Recent solutions include the use of coupled radiant and sub-radiant modes yielding narrow asymmetric Fano resonances in a wide range of systems, from defect states in photonic crystals and optical waveguides with mesoscopic ring resonators to nanoscale plasmonic and metamaterial systems exhibiting interference effects akin to electromagnetically-induced transparency. Here we demonstrate theoretically and confirm experimentally a new mechanism of resonant electromagnetic transparency, which yields very narrow isolated symmetric Lorentzian transmission lines in toroidal metamaterials. It exploits the long sought non-trivial non-radiating charge-current excitation based on interfering electric and toroidal dipoles that was first proposed by Afanasiev and Stepanovsky in [J. Phys. A Math. Gen. 28, 4565 (1995)].
238 citations
TL;DR: Coupling optical gain medium with high Q-factor toroidal resonance mode can enhance the single pass amplification to up to 65 dB, offering an opportunity of creating the “toroidal” lasing spaser, a source of coherent optical radiation that is fueled by toroidal plasmonic oscillations in the nanostructure.
Abstract: Toroidal shapes are often found in bio-molecules, viruses, proteins and fats, but only recently it was proved experimentally that toroidal structures can support exotic high-frequency electromagnetic excitations that are neither electric or magnetic multipoles. Such excitations, known as toroidal moments, could be playing an important role in enhancing inter-molecular interaction and energy transfer due to its higher electromagnetic energy confinement and weaker coupling to free space. Using a model toroidal metamaterial system, we show that coupling optical gain medium with high Q-factor toroidal resonance mode can enhance the single pass amplification to up to 65 dB. This offers an opportunity of creating the "toroidal" lasing spaser, a source of coherent optical radiation that is fueled by toroidal plasmonic oscillations in the nanostructure.
121 citations
TL;DR: In-situ X-ray absorption spectroscopy is performed to monitor the plasmonic-generating electromagnetic field upon the interface between ZnO/Ag nanostructures to reveal induced vacancies on the conduction band of Zn O, which allow effective separation of charge carriers and improves the efficiency of hydrogen generation.
Abstract: A new fabrication strategy in which Ag plasmonics are embedded in the interface between ZnO nanorods and a conducting substrate is experimentally demonstrated using a femtosecond-laser (fs-laser)-induced plasmonic ZnO/Ag photoelectrodes. This fs-laser fabrication technique can be applied to generate patternable plasmonic nanostructures for improving their effectiveness in hydrogen generation. Plasmonic ZnO/Ag nanostructure photoelectrodes show an increase in the photocurrent of a ZnO nanorod photoelectrodes by higher than 85% at 0.5 V. Both localized surface plasmon resonance in metal nanoparticles and plasmon polaritons propagating at the metal/semiconductor interface are available for improving the capture of sunlight and collecting charge carriers. Furthermore, in-situ X-ray absorption spectroscopy is performed to monitor the plasmonic-generating electromagnetic field upon the interface between ZnO/Ag nanostructures. This can reveal induced vacancies on the conduction band of ZnO, which allow effective separation of charge carriers and improves the efficiency of hydrogen generation. Plasmon-induced effects enhance the photoresponse simultaneously, by improving optical absorbance and facilitating the separation of charge carriers.
77 citations
TL;DR: In this paper, the synthesis of few-layer graphene sheets on an ultra-thin nickel film-coated SiO2/Si substrate using hydrogen-free plasma-enhanced chemical vapor deposition (PECVD) with in situ low-temperature carbon dissolution is preliminarily demonstrated.
Abstract: The synthesis of few-layer graphene sheets on an ultra-thin nickel film-coated SiO2/Si substrate using hydrogen-free plasma-enhanced chemical vapor deposition (PECVD) with in situ low-temperature carbon dissolution is preliminarily demonstrated. The deposited carbon atoms are initially dissolved into the nickel matrix and subsequently precipitate out onto the nickel film surface. The threshold carbon dissolution temperature for synthesizing few-layer graphene is observed to be as low as 475 °C, and the critical thickness of the host nickel film is at least 30 nm. Due to the ultra-low solubility of the carbon atoms in the nickel film at a threshold temperature of 475 °C, the layer number in few-layer graphene can be precisely controlled. Raman scattering analysis indicates almost identical D and 2D peak intensities for nickel films with different thicknesses, whereas the G peak is enhanced with an increasing layer number of graphene which precipitates from thicker nickel films. Saturation of the G peak for the 50 nm thick nickel film is observed, due to the finite carbon dissolution within a limited deposition time, and results in a stabilized, high quality precipitated few-layer graphene. The linear transmittance of few-layer graphene at 550 nm increases from 83 to 93% when the deposition time is shortened from 600 to 100 s, which corresponds to a decrease of the graphene layer number from 8 to 3 layers. The Raman scattering peak ratio of ID/IG decreases from 1.8 to 0.2 and the G-band linewidth shrinks from 67 to 37.2 cm−1, providing strong evidence for the improved quality of few-layer graphene synthesized by hydrogen-free PECVD at the threshold temperature on an ultra-thin nickel host.
74 citations
TL;DR: This work demonstrates a simple route for synthesizing multi-functional fluorescent nanodiamond-gold/silver nanoparticles, which is non-cytotoxic, supports long-term tracing and can be used in highly efficient photothermal therapy against cancer cells.
Abstract: This work demonstrates a simple route for synthesizing multi-functional fluorescent nanodiamond-gold/silver nanoparticles. The fluorescent nanodiamond is formed by the surface passivation of poly(ethylene glycol) bis(3-aminopropyl) terminated. Urchin-like gold/silver nanoparticles can be obtained via one-pot synthesis, and combined with each other via further thiolation of nanodiamond. The morphology of the nanodiamond-gold/silver nanoparticles thus formed was identified herein by high-resolution transmission electron microscopy, and clarified using diffraction patterns. Fourier transform infrared spectroscopy clearly revealed the surface functionalization of the nanoparticles. The fluorescence of the materials with high photo stability was examined by high power laser irradiation and long-term storage at room temperature. To develop the bio-recognition of fluorescent nanodiamond-gold/silver nanoparticles, pre-modified transferrin was conjugated with the gold/silver nanoparticles, and the specificity and activity were confirmed in vitro using human hepatoma cell line (J5). The cellular uptake analysis that was conducted using flow cytometry and inductively coupled plasma mass spectrometry exhibited that twice as many transferrin-modified nanoparticles as bare nanoparticles were engulfed, revealing the targeting and ease of internalization of the human hepatoma cell. Additionally, the in situ monitoring of photothermal therapeutic behavior reveals that the nanodiamond-gold/silver nanoparticles conjugated with transferrin was more therapeutic than the bare nanodiamond-gold/silver materials, even when exposed to a less energetic laser source. Ultimately, this multi-functional material has great potential for application in simple synthesis. It is non-cytotoxic, supports long-term tracing and can be used in highly efficient photothermal therapy against cancer cells.
50 citations
TL;DR: Results of this study demonstrate that heat-stable phosphate phosphors are promising candidates for increasing the efficiency of silicon-based solar cells.
Abstract: This study investigated the photoluminescent properties of Tb(3+)-Yb(3+)-, Ce(3+)-Tb(3+)-Yb(3+)-, and Eu(2+)-Yb(3+)-doped KSrPO4. The samples were prepared by a solid-state reaction with various doping concentrations. Emission at near-infrared range was focused on the application of luminescent solar concentrator for solar cells. Quantum cutting (QC) energy transfer was confirmed by the lifetimes of the donor. Near-infrared QC involved emission of Yb(3+) ions was achieved by excitation of Ce(3+), Tb(3+), and Eu(2+) ions, where the energy transfer processes occurred from Ce(3+) to Tb(3+) to Yb(3+), Tb(3+) to Yb(3+), and Eu(2+) to Yb(3+), respectively. In addition, the concentration quenching effect of Yb(3+) ions was avoided by low doping concentrations. The overall quantum efficiencies were calculated, and the maximum efficiency reaches 139%. The energy diagrams for divalent and trivalent rare-earth ions in KSrPO4 host lattice were analyzed. Results of this study demonstrate that heat-stable phosphate phosphors are promising candidates for increasing the efficiency of silicon-based solar cells.
44 citations
TL;DR: A low-cost and efficient photocatalytic reactor for environmental treatment and green technology was presented and the photoc atalytic efficiency and durability of the ZnO nanorods are effectively demonstrated.
Abstract: A low-cost and efficient photocatalytic reactor for environmental treatment and green technology was presented. ZnO nanorods firmly growing on polycarbonate optical disk substrate are generally perpendicular to the substrate as the immobilized photocatalyst of the spinning disk reactor. The photocatalytic efficiency and durability of the ZnO nanorods are effectively demonstrated.
42 citations
TL;DR: This lens is made of two hyperbolic metamaterials with different signs in their dielectric tensor and different isofrequency dispersion curves and has great potential applications in photolithography and real-time nanoscale imaging.
Abstract: We propose and analyze an innovative device called “Hybrid-Super-Hyperlens”. This lens is made of two hyperbolic metamaterials with different signs in their dielectric tensor and different isofrequency dispersion curves. The ability of the proposed lens to break the optical diffraction limit is demonstrated using numerical simulations (with the resolution power of about λ/6). Both a pair of nano-slits and a nano-ring can be imaged and resolved by the proposed lens using the radially polarized light source. Such a lens has great potential applications in photolithography and real-time nanoscale imaging.
40 citations
TL;DR: In this article, the preparation and properties of plasmonic gold nanostars (Au NSs) modified with a biopolymer chitosan are reported and the colloidal stability of Au NSs at the physiological pH of 7.5 and their performance in the photothermolysis of cancer cells in vitro were compared with those of gold nanorods.
Abstract: The preparation and properties of plasmonic gold nanostars (Au NSs) modified with a biopolymer chitosan are reported. The colloidal stability of Au NSs at the physiological pH of 7.5 and their performance in the photothermolysis of cancer cells in vitro were compared with those of gold nanorods (Au NRs). The optical characteristics of chitosan-modified Au NSs dispersed in a medium with pH = 7.5 had higher stability than those of chitosan-capped NRs because of the slower aggregation of NSs. At pH = 7.5, the chitosan-modified Au NRs formed aggregates with highly nonuniform sizes. On the other hand, Au NSs formed small chain-like clusters, in which individual NSs were connected to one another, preferably via association of branches with central cores. It is possible that the difference in areal charge density at these parts of NSs is responsible for their preferred association. Flow cytometry analysis showed the relatively nonequivalent distribution of the chitosan-capped Au NRs across the cell line compared...
38 citations
TL;DR: Ag nanostructures with surface-enhanced Raman scattering (SERS) activities have been fabricated by applying laser-direct writing (LDW) technique on silver oxide (AgOx) thin films and multi-level Raman imaging of organic molecules adsorbed on the nanostructure has been observed.
Abstract: Ag nanostructures with surface-enhanced Raman scattering (SERS) activities have been fabricated by applying laser-direct writing (LDW) technique on silver oxide (AgOx) thin films. By controlling the laser powers, multi-level Raman imaging of organic molecules adsorbed on the nanostructures has been observed. This phenomenon is further investigated by atomic-force microscopy and electromagnetic calculation. The SERS-active nanostructure is also fabricated on transparent and flexible substrate to demonstrate our promising strategy for the development of novel and low-cost sensing chip.
37 citations
TL;DR: The analysis has shown that the waveguide loss is sufficiently low for the QCL to reach its threshold at the injection current density around 6 kA/cm2 at room temperature.
Abstract: We propose and study the feasibility of a THz GaN/AlGaN quantum cascade laser (QCL) consisting of only five periods with confinement provided by a spoof surface plasmon (SSP) waveguide for room temperature operation. The QCL design takes advantages of the large optical phonon energy and the ultrafast phonon scattering in GaN that allow for engineering favorable laser state lifetimes. Our analysis has shown that the waveguide loss is sufficiently low for the QCL to reach its threshold at the injection current density around 6 kA/cm2 at room temperature.
TL;DR: Upon controlling the geometry of the plasmonic structures, the height, position, and pattern of scattered light can be modifi ed as desired, and it is shown that a simple and effient way to project a specifi c light pattern into free space, and demonstrate the capability of three-dimensional light manipulation.
Abstract: photovoltaics, [ 5 ] super-resolution imaging, [ 6 ] and various twodimensional plasmonic lens. [ 7 ] Besides, using nanostructures to project SPP plane waves into the adjacent free space is also an important issue. The interactions of plasmonic nanostructure on SPP wave involve not only the in-plane behavior, but also out-of-plane scattering which is captured as the far-fi eld radiated light. [ 8 ] A few theoretical approaches to convert the confi ned surface plasmons into radiated waves have been proposed. [ 9 ] It is highly desirable to extend the application range of plasmonic devices into the domain of three-dimensional light manipulation. [ 10 ] Recently, three-dimensional focusing and diverging of SPP waves by a quarter circular structure composed of gold (Au) nanobumps were studied. [ 11 ] The forward and backward scattering from individual Au nanobump are observed above and below Au surface, respectively. Hence, the Au nanobumps confer additional three-dimensional propagating wave vectors ( k x , k y , k z ) on SPP wave for departing from surface. Therefore, it is possible to manipulate the three-dimensional plasmonic scattering into specifi c geometry by arranging the Au nanobumps, which is schematically depicted in Figure 1 a. In this paper, we manipulate the scattering of SPP waves by various plasmonic structures composed of arranged nanobumps on a gold thin fi lm. Upon controlling the geometry of the plasmonic structures, the height, position, and pattern of scattered light can be modifi ed as desired. It provides a simple and effi cient way to project a specifi c light pattern into free space, and demonstrate the capability of three-dimensional light manipulation.
TL;DR: In this paper, the graphite nano-sheets obtained at different exfoliation bias show relatively stable saturable absorption and passive mode-locking performance in Erbium doped fiber lasers (EDFLs).
Abstract: Without the need of single-layer graphene, the graphite nano-sheet powder electrochemically exfoliated from graphite foil can also be employed as a stable saturable absorber and mode-locker for fiber lasers. High-quality graphite nano-sheets containing few graphene layers can be obtained by slow electrochemical exfoliation without the need of post annealing procedure. With reducing the electrochemical exfoliation bias of the graphite foil based anode from + 6 and + 3 volts, the electrochemically exfoliated graphite nano-sheets reveals a decreased D-band intensity in Raman scattering spectrum, and the 2D-band intensity is concurrently enlarged by two times to support the improved quality with suppressed oxidation during the exfoliation reaction. The X-ray photoelectron spectroscopy also confirms the suppression of the C-O bonds in the graphite nano-sheets obtained with decreasing the exfoliation bias. After centrifugation, the average diameter of the exfoliated graphite nano-sheets extracted from the acetone solution is shrunk from 7 μm to 100 nm as the anode bias decreases from 6 to 3 volts. Both the quality and size distribution of the graphite nano-sheets are improved with such slow but refined electrochemical exfoliation. In application, the graphite nano-sheets obtained at different exfoliation bias show relatively stable saturable absorption and passive mode-locking performance in Erbium doped fiber lasers (EDFLs). Benefiting from the advantages of high-gain and strong pulse compression in the EDFL, the graphite nano-sheets with different modulation depths only behave as a mode-locking starter and show trivial influence to the pulse shortening in the mode-locked EDFL, indicating that the strong soliton compression mechanism dominates the generation of 430-450 fs pulsewidth in the EDFL passively mode-locked by graphite nano-sheets.
TL;DR: The model is based on the well-established Gersten-Nitzan model coupled to the modified Mie scattering theory of Bohren and Hunt in the long wavelength approximation and shows that the surface charge will generally lead to a blueshift in the resonance frequency and greater enhancements in the SERS spectrum.
Abstract: Motivating by recent experiments on surface enhanced Raman scattering (SERS) from colloidal solutions, we present here a simple model to elucidate the effects of extraneous surface charges on the enhanced Raman signal. The model is based on the well-established Gersten-Nitzan model coupled to the modified Mie scattering theory of Bohren and Hunt in the long wavelength approximation. We further introduce corrections from the modified long wavelength approximation to the Gersten-Nitzan model for the improvement of its accuracy. Our results show that the surface charge will generally lead to a blueshift in the resonance frequency and greater enhancements in the SERS spectrum. Possible correlations with the recent experiments are elaborated.
TL;DR: In this article, a hybrid-superlens hyperlens with superresolution capabilities was proposed, which consists of two multilayered metal-dielectric anisotropic metamaterials.
Abstract: This study proposes an innovative device called “Hybrid-Superlens Hyperlens” with superresolution imaging ability and confirms it by using simulation. This device consists of two multilayered metal-dielectric anisotropic metamaterials: the upper planar superlens and the lower cylindrical hyperlens with different signs in their dielectric tensors and different isofrequency dispersion curves. In our simulation, 100-nm center-to-center resolution is obtained by using an incident wavelength of 405 nm, which is smaller than the optical diffraction limit.
TL;DR: In this paper, a switchable metamaterial working at terahertz (THz) regime was realized by using MEMS fabrications, where the resonance induced by 2.60-THz incidence was switched by reconfiguring the metammaterial element, which was analyzed using the coupled oscillators model.
Abstract: This paper reports a switchable metamaterial working at terahertz (THz) regime, which is realized by using MEMS fabrications. The resonance induced by 2.60-THz incidence is switched by reconfiguring the metamaterial element, which is analyzed using the coupled oscillators model. The resonance switching of the metamaterial has potential applications, such as optical switching, tunable filtering, THz sensing, etc.
TL;DR: The mode volume corresponding to each resonance is found to be squeezed over 10(4) smaller than the cube of incident wavelength, which may facilitate many applications in integrated optics, optical nonlinearities, and luminescence enhancement, etc.
Abstract: We fabricated a three-dimensional five-layered plasmonic resonant cavity by low-cost, efficient and high-throughput femtosecond laser-induced forward transfer (fs-LIFT) technique The fabricated cavity was characterized by optical measurements, showing two different cavity modes within the measured wavelength region which is in good agreement with numerical simulations The mode volume corresponding to each resonance is found to be squeezed over 10 4 smaller than the cube of incident wavelength This property may facilitate many applications in integrated optics, optical nonlinearities, and luminescence enhancement, etc
TL;DR: In this article, a plasmonic nano-antenna was proposed and numerically studied by means of the 3D finite element method, which is composed of two identical castle-like contour nanometal-filled dielectric media inside the hollows.
Abstract: We propose a new design of a plasmonic nanoantenna and numerically study its optical properties by means of the 3D finite element method. The nanoantenna is composed of two identical castle-like contour nanometal-filled dielectric media inside the hollows. We examine the influence of the contour thickness, gap width, and dielectric media filled inside the hollows on the antenna resonance conditions. Through these simulations, we show that it is possible to tune an antenna with a constant length over a broad spectral range (ranging in ultraviolet–visible, visible light, and infrared light).
TL;DR: Numerical results show that while charge effects will in general blue-shift all the plasmonic resonances of the metal particle, both the quantum yield and the fluorescence yield can be increased at emission frequencies close to that of the surface plAsmon resonance of the particle due to the suppression of the nonradiative decay rate.
Abstract: The modified fluorescence properties of a molecule in the vicinity of a metallic nanoparticle are further studied accounting for the possible existence of extraneous charges on the particle surface. This is achieved via a generalization of the previous theory of Bohren and Hunt for light scattering from a charged sphere, with the results applied to the calculation of the various decay rates and fluorescence yield of the admolecule. Numerical results show that while charge effects will in general blue-shift all the plasmonic resonances of the metal particle, both the quantum yield and the fluorescence yield can be increased at emission frequencies close to that of the surface plasmon resonance of the particle due to the suppression of the nonradiative decay rate. This provides a possibility of further enhancing the particle-induced molecular fluorescence via the addition of surface charge to the metal particle.
TL;DR: In this paper, the light absorption of a plasmonic photocatalyst in the circular plane waveguide of a photocatalytic spinning disk reactor was investigated, and the authors used a diffusion coupler to demonstrate the effect of light absorption.
Abstract: This study numerically investigates the light absorption of a plasmonic photocatalyst in the circular plane waveguide of a photocatalytic spinning disk reactor The degradation of methyl orange (MO) in water with a dual light source spinning disk reactor (DL-SDR) and embedded diffusion coupler demonstrates the plasmonic photocatalytic reaction When light propagates in the circular plane disk (CPD) waveguide of a DL-SDR, it gradually loses energy because of the absorption of the photocatalyst This absorption boosts the processing efficiency of the plasmonic photocatalytic reaction A real case by a diffusion coupler was used to present the plasmonic photocatalytic reaction This study presents the numerical analysis of a secondary optical lens (SOL) coupler and the numerical evaluation of light absorption of the plasmonic photocatalyst in a DL-SDR An elliptical reflector collects the light emitted from the circular ring edge of the SOL and CPD This study presents an evaluation method that simulates the light absorption of a photocatalyst coating on the CPD of a DL-SDR
Posted Content•
TL;DR: In this article, the authors demonstrated that the electric and magnetic resonances can be separately switched off and on by positioning the metamaterials along a standing wave, while both resonances are present in travelling-wave spectra.
Abstract: In a proof-of-principle experiment with metamaterials exhibiting electric dipolar and magnetic dipolar resonances, we demonstrated that the electric and magnetic resonances can be separately switches off and on by positioning the metamaterials along a standing wave, while both resonances are present in travelling-wave spectra.
TL;DR: In this article, a plasmonic multilayer structure was modified to an asymmetric one and a nanoporous Au film was proposed to act as a bandstop filter.
Abstract: Various types of free-space plasmonic bandstop filters are reviewed. The plasmonic multilayer structure shows multiple localized surface plasmon (LSP) resonance modes with extraordinary high angle tolerance. Through modifying the plasmonic multilayer structure to a plasmonic T-shaped array, the multiple LSP modes can be suppressed. The filtering properties present a single resonance dip with a low sideband. Through modifying the plasmonic T-shaped array to be an asymmetric one, dual resonance modes can be easily designed. Finally, a nanoporous Au film is proposed to act as a bandstop filter. The fabrication processes are simple and the resonance dip can be manipulated by altering the annealing temperature.
TL;DR: In this paper, the authors proposed a new technique to grow tunable, non-spherical gold/silver NPs using a simple, rapid Figure 1. Transmission-electron-microscopy bright-field images of gold and silver nanocrystals synthesized with various gold/ silver ratios.
Abstract: Many metal nanoparticles (NPs) are being studied for use in photothermal cancer therapy, a non-invasive technique where specific wavelengths of light can be used to excite the NPs, causing local heating that selectively kills cancer cells. These NPs can convert light to heat because of surface plasmon resonance, where electrons oscillate at the surface of the NPs resulting in specific absorbance or scattering. Plasmonic metal NPs have attracted enormous interest because their physical and chemical properties can be tuned by changing the size, shape, and composition of the nanostructures. Experimental and theoretical results have shown that nonspherical NPs, such as branched or urchin-like ones, exhibit stronger electromagnetic behavior than spherical NPs, making them more effective for photothermal therapy.1 Moreover, anisotropic gold NPs exhibit numerous plasmon resonances in the visible and near-IR range, which depend strongly on polarization. However, anisotropic NPs require long synthesis times, and they are unstable at room temperature. These issues limit their use. Branched gold NPs can be obtained by several methods, the most common is the seeded growth approach. While the morphology of the resulting NPs can be tuned by several factors in the seeded growth approach,2 the process is lengthy and complicated. Seedless synthesis is another route to save time, but the NP morphology cannot be well-tuned, which limits its efficiency in bio-applications.3 We created a new technique to grow tunable, non-spherical gold/silver NPs using a simple, rapid Figure 1. Transmission-electron-microscopy bright-field images of gold/silver nanocrystals synthesized with various gold/silver ratios: (a) 3, (b) 10, (c) 15, (d) 30, (e) 50 and (f) 100.5
16 Jun 2013
TL;DR: In this paper, a microfluidic nanoparticles sorting generator using optical force and hydrodynamic forces is presented, where the particles with different sizes and refractive indices can be selected by the optical forces and the drag force.
Abstract: This paper reports a microfluidic nanoparticles sorting generator by using optical force and hydrodynamic forces. Nanoparticles ranges in size from 70 nm to 1 μm can be aligned and focused in the core flow stream by hydrodynamic focusing. By injecting light into the microfluidic system, the particles can be subsequently manipulated by the optical forces and liquid Stoke forces. The particles with different sizes and refractive indices can be selected by the optical forces and the drag force, flowing with different traces. It has a great potential in cell and molecule sorting and separating.
TL;DR: Optical interference coatings designed for use in a space-grade multispectral assembly in a complementary metal-oxide-semiconductor sensor were deposited on glass by ion-beam-assisted deposition for a Cassegrain-type space-based remote-sensing platform.
TL;DR: In this article, a method of comparing the speeds of starlight and the light emitting from a terrestrial source was presented to detect the effect of the relative velocity on the measurement of the speed of light.
Abstract: The speed of light is an important physical parameter. Currently it is a common belief of the constance of the speed of light regardless of the relative velocity between the source and the observer. Because the speed of light is very fast, if the relative velocity is small compared with the speed of light, it is difficult to detect the effect of the relative velocity on the measurement of the speed of light. In this paper we present a method of comparing the speeds of starlight and the light emitting from a terrestrial source. We use a telescope to collect the light from the star having significant relative velocity with respect to the earth, e.g. Capella. Then we modulate the starlight and the light emitted from the local source into pulses i.e. these pulses leave the modulator simultaneously. After travelling 4.2 km, these pulses are detected by a receiver. If the starlight and the terrestrial light have the same speed, then these pulses must arrive at the receiver at the same time. Our results show that the arrival times of the pulses of starlight are different from that of the local light. For example, the Capella is leaving away from the earth. The Capella pulses arrive later than the local light pulses. It indicates that the speed of Capella starlight is slower than the common believed value, c. The presented method uses one clock and one stick, so the clock synchronization problem and any physical unit transformation can be avoided.
Patent•
15 Mar 2013
TL;DR: In this paper, an image-based diopter measuring system consisting of an optical device and an electronic device is presented, where the optical device is used to guide an external light which is passed through an analyte.
Abstract: An image-based diopter measuring system comprises an optical device and an electronic device. The optical device is used to guiding an external light which is passed through an analyte. The electronic device comprises an image capture module, an image analyze module and a display module. The image capture module generates a first image by capturing the external light source. The image analyze module connects to the image capture module to receive the first image, and analyzes the first image in order to generate an analytical result comprising the diopter of the analyte. The display module connects to the image analyze module to receive and display the analytical result.
TL;DR: In this paper, a V-shaped antenna array metastring supports anomalous reflection and refraction of incident light but has the drawback of low conversion efficiency, while in this paper, we propose a new metasurface that functions as the perfect link between propagating waves and surface waves.
Abstract: Photonics research and novel applications require an ability to manipulate light. Much can already be achieved with natural materials, but their permittivity and permeability are limited. However, artificial metamaterials (MTMs), which are made of electromagnetic (EM) microstructures in deep-subwavelength scales, operate as an effective medium with almost arbitrary permittivity and permeability and thus offer greater freedom to control light. Homogeneous MTMs have been shown to offer interesting effects such as negative refraction and a perfect lens.1, 2 Slowly varying inhomogeneous MTMs have separately realized invisibility cloaking for propagating waves (PWs)3–5 and surface waves (SWs).6, 7 Recently, the extraordinary light-manipulation abilities of ultrathin MTMs (i.e., metasurfaces) with abruptly varying material properties have attracted much attention. A V-shaped antenna array metastring supports anomalous reflection and refraction of incident light but has the drawback of low conversion efficiency.8, 9 In previous work, some of us introduced a new metasurface that functions as the perfect link between PWs and SWs.10 Unlike with slowly varying inhomogeneous MTMs,3–7 EM waves do not stay inside ultrathin gradient metasurfaces for a long time. As a result there is less scattering, phase distortion, and dissipation. The metasurfaces offer great versatility for manipulating light, for instance, for anomalous reflection,8, 9 an antireflection coating, and a highly efficient surface plasmon polariton (SPP) coupler (an SPP is a quasiparticle of light and electron waves).10 Figure 1. Schematics of the designed sample with a unit cell (inset) consisting of a gold (Au) nanorod (yellow) and a continuous Au film (yellow) separated by a magnesium fluoride (MgF2) spacer (blue). L, w, d1: Length, width, and depth of the nanorod, respectively. L1; 2: x, y dimensions of the unit cell, respectively. d2; 3: Depth of the MgF2 spacer and the Au film, respectively. Lx; y : x, y dimensions of the repeating unit, respectively.
12 May 2013
TL;DR: In this paper, the authors report on the experimental demonstration of a new radiation phenomenon on the nanoscale and its engineering into a reconfigurable metadevice: luminescence emission lines within the Fermi sea can be created by nanopatterning metal surfaces and tuned by external electrical inputs.
Abstract: We report on the experimental demonstration of a new radiation phenomenon on the nanoscale and its engineering into a reconfigurable metadevice: luminescence emission lines within the Fermi sea can be created by nanopatterning metal surfaces and tuned by external electrical inputs.